HRIBF Newsletter, Edition 15, No. 1, Feb. 2007

Feature Articles

Regular Articles

RA1. RIB Development
RA2. Accelerator Systems Status
RA3. Experimental Equipment/Technique - A Novel Approach for Measurement of (p,alpha) Reactions
RA3. Users Group News
RA4. Suggestions Welcome for New Beam Development
RA5. HRIBF Experiments, July - December 2006

1. HRIBF Update and Near-Term Schedule
(J. R. Beene)

In the last issue of this newsletter, I began my "Update" with the sentence: "Fiscal 2006 will be a good year to get behind us." This has proved to be harder than was anticipated. As of January 2007, HRIBF is still operating under a Continuing Resolution, at the extremely austere funding levels of the fiscal 2006 budget. This budget is ~18% lower than the FY2007 President's Request. The FY2006 budget represented an approximately 7% cut compared to FY2005; it was inadequate to operate HRIBF efficiently and effectively, even on our 5-day per week schedule. Staff costs have risen about 10% since FY2006 and overall operating costs are about 7% higher. If the worst-case scenario of FY2007 funding at the FY2006 level comes to pass, we plan to cease facility operations in early April and remain in shutdown (at least for RIB operations) for the remainder of the fiscal year. HRIBF, of course, is not alone in facing severe difficulty if a full year at FY2006 levels comes to pass. This dire result erases substantial increases across many DOE Office of Science research programs. Nuclear physics is particularly hard hit because of the sharp cuts in the NP budget in FY2006.

RIB operations are off to an excellent start in FY2007, as we operated the facility aggressively in anticipation of the favorable funding in the Presidents Request. From October through the first week in December, when we shut down for scheduled maintenance, we provided over 700 hours of RIB to experiments out of 1115 total research hours. For the most part these were very difficult beams, including a very rewarding series of decay spectroscopic studies on short-lived Cu and Ga isotopes using post-accelerated beams of ^76-79Cu and ^83-85Ga (see item 3 of this newsletter). The longest-lived of these isotopes has a halflife of 0.65 seconds, and ^84,85Ga have halflives less than 100 ms. This is a major achievement for our ISOL development group. It is worth noting that in the last six months before the December shut down, we delivered 1500 h of RIB to experiments. Well done! The tandem tank opening (see RA2 of this newsletter), which is the major element of the shutdown, is proceeding according to schedule. Prior to the shutdown, the tandem set a record for continuous operation without major maintenance. The availability of the HPTL has given us added flexibility to schedule full-power ISOL development work during the tandem shutdown. Unfortunately, the looming budget shortfall has forced us to limit HPTL operation to about two weeks during this period.

After the shutdown is complete in mid February, we plan one week of stable beam delivery at low terminal voltage, followed by a six-week neutron-rich RIB campaign. At this point, we will shut down RIB operations if funding remains at FY2006 levels. If more favorable funding develops, we plan to stage a radioactive fluorine campaign followed by another neutron-rich campaign of about 8 weeks each, with stable beam runs used to fill time for RIB target ion source changeovers, etc. We are extremely anxious to have the opportunity to demonstrate what we can accomplish with the level of funding which we had expected in FY2007.

2. Recent HRIBF Research - (d,p) Reactions on ¹³⁰Sn and ¹³²Sn in Inverse Kinematics
(R. L. Kozub, spokesperson RIB-134; K.L. Jones, spokesperson RIB-132)

The r-process is thought to be responsible for the synthesis of about half of the nuclear species heavier than Fe [Bu57], but little experimental information is available for nuclear structure and the r-process near the N=82 closed neutron shell and the A~130 abundance peak. The r-process is most productive where neutron-rich nuclei far from stability have high level densities and find themselves in an environment of sufficiently high neutron density that the rate of neutron capture exceeds the rate of beta-decay. In such cases, statistical (Hauser-Feshbach) methods can be used to predict the cross sections for reaction rate calculations by averaging over resonances. However, for nuclei far from stability that are near the magic numbers N=50, 82, and 126, the level densities are too low for a statistical approach [Ra97], and it is thus necessary to input the single-particle structure of individual levels. The (d,p) neutron transfer reaction has proven to be an excellent tool for the measurement of these single-particle properties, which are also critically needed for the development of structure models for all nuclei. We report here some very preliminary results from two recent experiments in which beams of ¹³⁰Sn and doubly magic ¹³²Sn were used to measure single-particle properties of ^131,133Sn via the ²H(^130,132Sn, p)^131,133Sn reactions.

The information known to date on ¹³³Sn has come from gamma-ray transitions following the ¹³⁴In(beta)¹³⁴Sn*(n)¹³³Sn* decay sequence [Ho96] and the fission of ²⁴⁸Cf [Ur99], both of which favor the population of states having J≥3/2. Low-lying pf-shell states and the h_9/2 state have thus been located, but there is no single-particle information available. Further, not even the location has been firmly established for the expected p_1/2 state.

Yrast cascades in ¹³¹Sn involving states with J≥11/2 have been studied by Bhattacharyya, et al. [Bh01], and some of the low-lying, positive-parity hole states have been assigned tentatively [Se94] from beta-decay experiments. In the (d,p) reaction, however, one expects the strongest states to be l=1 and l=3 transfers coupled to the ¹³⁰Sn ground state, i. e., negative-parity 1p-2h states, none of which has been identified.

In the present work, radioactive beams of 630-MeV ¹³²Sn and ¹³⁰Sn ions bombarded an 80 micrograms/cm²-thick CD₂ foil. In order to detect protons near 90° in the laboratory, the target surface was placed at 30° with respect to the beam axis, so the effective thickness was 160 micrograms/cm². Protons from the reactions were detected with an array of position-sensitive silicon strip detectors,including 14 of the new ORRUBA detectors, with half of SIDAR and a 5x5cm position sensitive telescope.

Some samples of the online data from these experiments are shown in Figs. 2-1 and 2-2. In Fig.2-1, four states can be observed in ¹³³Sn, presumably the f_7/2 ground state, and the p_3/2, p_1/2, and f_9/2 excited states. All but the p_1/2 appear to have kinematics in agreement with published data for the mass/excitation energies. The first result from this experiment is expected to be the location of the p_1/2 single-particle state in ¹³³Sn . A similar pattern at roughly similar Q-values (higher excitation energies in ¹³¹Sn) is observed in the ²H(¹³⁰Sn,p)¹³¹Sn reaction (Fig. 2-2). Angular distributions will be extracted, pursuant to determining J assignments and measuring spectroscopic factors. Analysis of the data is ongoing.

Figure 2-1: Energy versus angle plot of ²H(¹³²Sn,p)¹³³Sn events from one of the "forward" position-sensitive strip detectors. Most elastic scattering events were stopped by the 65-μm-thick ΔE detector in front of this detector. Also shown are expected ²H(¹³²Sn,p)¹³³Sn kinematics loci for known states in ¹³³Sn. Excitation energies shown are in keV.

Figure 2-2: Energy versus angle plot of ²H(¹³⁰Sn,p)¹³¹Sn events from one of the "forward" position-sensitive strip detectors. All elastic scattering events were stopped by the 140-μm-thick ΔE detector in front of this detector. The gain is approximately the same as in Fig.2-1.

[Bu57] E. M. Burbidge et al., Rev. Mod. Phys. 29, 547 (1957).
[Bh01] P. Bhattacharyya, et al., Phys. Rev. Letters 87, 062502 (2001).
[Ho96] P. Hoff et al., Phys. Rev. Lett. 77(6) 1020 (1996).
[Ra97] T. A. Rauscher et al., Nucl. Phys. A621, 327c (1997).
[Se94] Yu. V. Sergeenkov, et al., Nuclear Data Sheets 72, 487 (1994).
[Ur99] W. Urban et al., Eur. Phys. J. A5, 239 (1999).

3. Recent HRIBF Research - Decay Studies of ^76-79Cu and ^83,84Ga
(J. A. Winger, Spokesperson)

In recent years there has been increased interest in the study of nuclear structure near the doubly magic nuclide ⁷⁸Ni. This has come about as new techniques have allowed the production and separation of these nuclides. At the HRIBF, we have developed a technique using re-accelerated isobarically separated beams to obtain pure beams or beams with enhanced purity. In this technique, a beam from the high voltage platform is isobarically purified before being accelerated through the tandem. The energy of the beam is high enough to allow it to pass through an ion chamber before the beam is deposited onto a moving tape collector (MTC). Using the ion chamber to identify the components of the beam, the isobaric separator can be fine tuned to provide optimal beam purity. Decay spectroscopy of the purified beams is performed using a CARDS array fitted with four Clover detectors and two plastic β detectors.

Two modes of operation are available. At pressures near 200 torr, the higher-Z components are stopped in the gas or exit window of the ion chamber thereby enhancing the purity of the lowest-Z component of the beam. In the case of Cu ions, the removal of Zn from the beam in the charge exchange cell allowed for pure beams. The ions are stopped on the MTC at a position just past the exit of the ion chamber and then moved into the CARDS array. This method is effective for studying long-lived (>1s) nuclides or the daughters (i.e., Zn). At lower pressures (about 100 torr), the deposition point is moved back to the center of the CARDS array allowing the study of short-lived nuclides. In our experiment, the ion chamber was used to identify all ions entering the system, allowing continuous knowledge of the beam composition. In the low pressure mode this allowed the tagging of the ions which could be correlated with the decays in a short time window following implantation. With this method, it was possible to observe decays at rates down to 0.1 ion per second. Although it was not attempted in the current experiment, it is possible to run the ion chamber in a passive mode with the voltage turned off in order to purify beams with much higher beam rates.

For ^76,77Cu, both techniques were used to determine the β-delayed neutron branching ratios by comparison of the primary γ rays from the Zn daughters of the two branches. Spectra for these two measurements are shown in Fig. 3-1. This measurement was greatly simplified by the lack of Zn isotopes in the beam. For ⁷⁷Cu a number of γ rays were assigned to the decay and will be used to produce a decay scheme. In ⁷⁸Cu decay, we observed the 907→891→730 keV decay sequence from the yrast band, but found no evidence for the 145-keV transition out of the 8⁺ isomer. This suggests a 5^- or 6^- ground state for ^76,77Cu, but more analysis needs to be performed to confirm this result. For ⁷⁹Cu we were able to observe for the first time the 730-keV transition in ⁷⁸Zn fed by the β-delayed neutron branch but found no γ rays that could be assigned to the β branch. This implies a very large β-delayed neutron branch for this r-process nuclide.

Figure 3-1: Fitted spectra showing (a) the relative peak areas of the 199-keV peak from ⁷⁶Zn and the 228-keV peak from ⁷⁵Zn used to deduce the β-delayed neutron branch for ⁷⁶Cu, and (b) the 189-keV peak from ⁷⁷Zn and the 199-keV peak from ⁷⁶Zn used to deduce the β-delayed neutron branch for ⁷⁷Cu.

The decays of ^83,84Ga are dominated by γ rays fed through the β-delayed neutron branch. The intensity of these γ rays will be used to determine the β-delayed neutron branching ratios, but a more interesting result comes in looking into the states fed by the β decay branch. With ⁸³Ga we were able to observe a γ ray at 248 keV (with an approximate 0.5% branching ratio) which we assign as the transition between the νs_1/2 first excited state and the νd_5/2 ground state. This assignment is supported by observation of the same γ ray in the decay of ⁸⁴Ga as shown in Fig. 3-2. In ⁸⁴Ga decay we also observe a γ ray at 623 keV which we tentatively assign as being the 2₁⁺→0₁⁺ transition. Both γ rays are at lower energies than were expected from systematics of the N=51 and 52 isotones. In fact, the 623-keV γ ray indicates that E(2₁⁺) continues to drop below mid-shell which might indicate a weakening of the ⁷⁸Ni core for N>50.

Figure 3-2: Comparison of the spectra from ⁸³Ga (black line) and ⁸⁴Ga (red line) showing a γ ray at 248 keV present in both decays. Notice that nature was unkind in the case of ⁸³Ga decay with the 248-keV line being in a close doublet with a line from ⁸²Ge fed in the β-delayed neutron branch.

4. Recent HRIBF Research - Discovery of the Alpha Decay of ¹⁰⁹I
(C. Mazzocchi, spokesperson)

Particle-decay spectroscopy is often the only option to measure separation energies for short-lived nuclei with high precision and using only tens of ions. Moreover, alpha and proton decay are an incredibly rich source of nuclear structure information and can be used to probe the wave functions of the nuclear levels involved and to probe nuclear-shell effects, see e.g. [1]. Of particular interest is the region of the Segre chart above the doubly magic nucleus ¹⁰⁰Sn, where an island of alpha and proton emission exists. The occurrence of this alpha- and proton-radioactive nuclei directly reflects the strong N=Z=50 shell closures and the presence of the proton drip-line. Particularly interesting is the case of ¹⁰⁹I, which was discovered as a ~100% proton emitter [2] with 100 μs half-life and is expected to present a small but measurable alpha-decay branch [3]. Several attempts were carried on to observe the alpha-decay branch without any success. The measurement of its decay energy allows to indirectly and independently set the value of the proton separation energy (S_p=-Q_p) in the daughter nucleus ¹⁰⁵Sb, see Fig.4-1. The measurement of S_p(¹⁰⁵Sb) is of interest for the astrophysical rapid proton-capture process (rp-process), since the isotope is located on the predicted path for the process termination around the Sn-Sb-Te cycle, see Fig. 4-1.

Figure 4-1: Portions of the Segre chart above ¹⁰⁰Sn. Left panel: The nuclei of interest are represented by a filled box. The known alpha and proton decays of ¹⁰⁸Te and ¹⁰⁹I, respectively, are represented by solid arrows, while the proton decay of ¹⁰⁵Sb and the hitherto unobserved alpha-decay branch of ¹⁰⁹I through a dashed arrow. Right panel: Path followed by the rp-process in the ¹⁰⁰Sn region as predicted in [4].

At the HRIBF the ¹⁰⁹I nuclei were produced in the fusion-evaporation reaction ⁵⁸Ni⁵⁴(Fe,p2n)¹⁰⁹I. The recoiling evaporation residues were separated according to their mass-to-charge ratio by means of the Recoil Mass Spectrometer [5] and implanted into a double-sided silicon strip detector. The preamplifier signals were read out through the digital signal processing-based acquisition system [6]. The ion implantation and decay events were correlated in space and time.

In Fig.4-2, a portion of the alpha-decay energy spectrum of decay events is displayed. The two peaks at 3107- and 3317 keV corresponding to the alpha decays of ¹⁰⁹Te and ¹⁰⁸Te, respectively. The third peak at an energy of 3774�20 keV is assigned to the alpha decay of ¹⁰⁹I. The identification of these alpha events is supported by the observed decay pattern, in agreement with the remeasured 93.5(3) ms ¹⁰⁹I half-life. The energy of the alpha decay of ¹⁰⁹I corrected for the recoil effect gives Q_a=3918�22 keV. The branching ratio is ~0.0001.

Figure 4-2: Portion of the energy spectrum of decay events following implantation of an ion within 400 μs. The peaks are labeled with their precursor.

The measurement of the alpha decay energy of ¹⁰⁹I allows for the indirect measurement of the Q_p( ¹⁰⁵Sb): Q_a(¹⁰⁹I)+Q_p( ¹⁰⁵Sb)=Q_p(¹⁰⁹I)+Q_a( ¹⁰⁸Te), leading to Q_p(¹⁰⁵Sb)=356�22 keV. The new Q_p value of ¹⁰⁵Sb is in clear disagreement with that of 491�15 keV previously reported by Tighe et al. [7]. The Q_p value is though in agreement with the non-observation and relative limits set by other experiments searching for this decay branch of ¹⁰⁵Sb over the past 20 years.

In order to explore the impact of the new Q_p(¹⁰⁵Sb) on the rp-process, we ran reaction network calculations using the one-zone X-ray burst model described in [4]. The measured value of Q_p(¹⁰⁵Sb) excludes the formation of a Sn-Sb-Te cycle at tin isotopes with mass lower than 105.

[1] S.N. Liddick et al., Phys. Rev. Lett. 97 (2006) 082501.
[2] T. Faestemann et al., Phys. Lett. 137B (1984) 23.
[3] R.D. Page et al., Phys. Rev. C49 (1994) 3312.
[4] H. Schatz et al., Phys. Rev. Lett. 86 (2001) 3471.
[5] C.J. Gross et al., Nucl. Instrum. Methods Phys. Res. A450 (2000) 12.
[6] R. Grzywacz, Nucl. Instrum. And Methods Phys. Res. B204 (2003) 649.
[7] R. Tighe et al., Phys. Rev. C49 (1994) R2871.

5. What's New at HRIBF - Laser Ion Source Development
(Yuan Liu, Spokesperson)

We have recently made good progress in realizing a laser ion source to extend the RIB beam capability at HRIBF. New measurements of resonant laser ionization on several elements of interest have been recently conducted at HRIBF with a new commercial Ti:Sapphire laser and two additional Ti:Sapphire lasers from the University of Mainz. The commercial Ti:Sapphire laser was a prototype of the Ti:Sapphire laser that is being developed by Photonics Industries International, Inc, in Bohemia, New York. It will be the first commercial laser that meets the specific requirements for a resonant ionization laser ion source (RILIS) system. The Ti:Sapphire laser was procured in 2006 and the final product is expected to be delivered in 2007.

In collaboration with the research group led by Klaus Wendt of the University of Mainz, the Photonics Ti:Sapphire laser was successfully incorporated with two Ti:Sapphire lasers provided by the Mainz group and a standard hot-cavity surface ionization source developed at HRIBF. A 100-W Nd:YAG laser at 532 nm, also newly purchased by HRIBF, provided the required pump for the three Ti:Sapphire lasers. Shown in Fig.5-1 is a photo of the RILIS laser system and associated optical setup in operation at the HRIBF off-line Ion Source Test Facility 2 (ISTF-2).

Figure 5-1: The RILIS laser system used for the measurements at HRIBF.

Three photon ionizations of Sn, Ni, Mn, Fe and Al have been obtained with the new laser system. This work is the first time Mn and Fe ion beams are produced in a hot-cavity LIS using Ti:Sapphire lasers. More than 1.2 μA of Sn and Mn, and more than 500 nA of Ni laser ions were observed. The ionization schemes used for Mn and Fe are illustrated in Fig. 5-2. The final ionization step is of crucial importance for both the efficiency and selectivity of the RILIS. Resonant ionisation via autoionizing or Rydberg states can significantly increase the ionization efficiency and reduce the laser power needed for saturation of the transitions. The Photonics Ti:Sapphire laser is unique in (1) it uses only two mirror sets to cover the fundamental output range of 700-960 nm, and (2) it provides continuous wavelength tuning over the full wavelength range. Therefore, it is ideally suitable for RILIS applications with considerably simplified operation. Accordingly, spectroscopic studies of high lying Rydberg levels and autoionizing states in Ni, Mn, Fe, and Al were conducted using the Photonics Ti:Sapphire laser for the last ionization step. Both Rydberg states and autoionization states were successfully observed in Ni, Mn and Fe. The spectrum of the Rydberg levels in Mn is shown in Fig. 5-3. Analysis of the observed Rydberg and autoionization states is in progress.

This work is an important step in developing a state-of-the-art RILIS system based on all-solid-state Ti:Sapphire lasers for the HRIBF research program.

Figure 5-2: Three-photon excitation and ionization schemes for Mn and Fe.

Figure 5-3: Measured Rydberg series in Mn versus the wavelength of the third excitation step.

6. What's New at HRIBF - Update on Injector for Radioactive Ion Species 2 (IRIS2)
(B. A. Tatum )

All aspects of the IRIS2 Project are progressing well. The major effort in the facility modifications portion of the project has been associated with design, fabrication, and installation of the Target Room HVAC system. Design of this system was completed in the fall and a construction contract was subsequently awarded. The system will be installed and operable by April 1. Most of the project effort to date has been focused on design and procurement of long lead-time technical equipment components. Design of both high voltage platform structures has been finalized with National Electrostatics Corporation (NEC). The injector beamline platform will be received in May, and the instrumentation platform in August. Acceleration tubes have already been received. A contract for fabrication of the first stage mass separator magnets has been awarded to Sigma Phi. The rectangular dipole is slated to arrive in Oak Ridge in early July, and the two sector dipoles will arrive in late July. High voltage conduit design has been completed and components ordered. Abbott Plastics and their Canadian provider of polyethylene are producing the major components of the conduits. Each of the four conduits will consist of an aluminum pipe surrounded by an 18.5″OD x 8.5′ID x 16′long polyethylene extrusion. Delivery is expected by the end of January. After arrival at ORNL, the assembly will be inserted through rectangular polyethylene laminations for additional isolation and ease of insertion into the concrete shielding wall. ES Inc. has delivered the 10-foot extension of the HPTL crane and it has been installed. A portion of the automation package has also been received. The system should be fully operable by April. Support structure for localized shield around the target ion source has been fabricated, received, and partially installed. Both the upper and forward shielding sections will be movable and another side will be fixed. Fabrication of the individual shielding planks is also under way. Overall, the IRIS2 Project is on schedule and on budget.

7. The HRIBF Low energy Radioactive Ion Beam Spectroscopy Station (LeRIBSS)
(K. Rykaczewski, Spokesperson)

A new experimental end-station dedicated to decay spectroscopy studies, Low-energy Radioactive Ion Beam Spectroscopy Station (LeRIBSS), is presently under construction at the HRIBF. The construction of LeRIBSS is a joint effort between ORNL and HRIBF users interested in nuclear structure studies performed using decay spectroscopy methods. The construction is supported by the UNIRIB Consortium, with the Louisiana State University being the largest external contributor. The total cost, which includes the ORNL and LSU investments, is about $250k .

LeRIBSS is located behind the RIB injector magnet, at the bottom of the HRIBF Tandem accelerator, see Fig.7-1. It consists of a beam steerer and a focussing quadrupole, a universal detector support called CARDS, and a new moving fast tape collector. The space left behind the CARDS array in the initial configuration, see Fig.7-1, will allow us to accommodate the Multi-Turn Time-of-Flight (MTOF) mass spectrometer when it is ready for operation. CARDS can support several detectors, including Ge (clover, X-ray and gamma-X) gamma-counters, a fast timing BaF₂ array as well as high resolution electron detectors and β-counters. A proposed high-efficiency β-delayed neutron detector will also fit into the CARDS ring at LeRIBSS.

Figure 7-1: Schematic drawing of LeRIBSS in the RIB injection hall. The low energy radioactive beam, after being separated by the high resolution injector magnet, will be transmitted straight to the LeRIBSS tape collector.

LeRIBSS is strategically positioned at the HRIBF location, where the best quality and intensity Radioactive Ion Beams (RIBs) are available. In particular, it profits from the high-resolution injector magnet, which was designed to have a mass resolution ΔM/M better than 10^-4 . The transmission and mass resolution will be verified and optimized online during the commissioning of LeRIBSS. It is important to note that the experiments at LeRIBSS can be performed with negative as well as positively charged ions since transmission through the charge exchange cell is not required. Initial attempts to transmit low-energy 40-keV positive ions through the high-resolution injector magnet with reversed magnetic field direction were successful.

The LeRIBSS setup will also profit from the completion of the IRIS2 project (and hopefully from the newly proposed electron driver). The radioactive beams produced at the High Power Target Laboratory will be merged with the existing RIB delivery system in front of the high resolution injector magnet. This means that at LeRIBSS we can perform experiments with the mass separated radioactive ions produced at both RIB platforms. Ion energies of about 200 keV should be large enough to provide an implantation timing signal from the Microchannel Plate detector equipped with a 10 μg/cm² carbon foil and improve the signal/background ratio using the implantation-decay time correlations.

The time scale of completing of the construction work of the LeRIBSS ion optics is funding dependent. We hope to be ready for first experiments in CY 2007.

8. A Photo-fission Driver Upgrade for HRIBF
(J. R. Beene )

The HPTL is complete, and the IRIS2 project is underway and proceeding well. The next step in our strategic plan for improvement of the HRIBF is a driver accelerator upgrade. We will propose to improve our RIB production capability by installing a turn-key electron accelerator capable of delivering a 100-kW beam, at an energy in the range 25 to 50 MeV. This is the most cost-effective way to achieve leadership class capability in our neutron-rich beam program. With existing HRIBF target technology, and modest-sized targets (~180 g U), such a facility will be capable of generating 10¹³ photo-fissions per second. For our baseline design, the beam power required to reach this fission rate is 50 to 60 kW (depending on electron beam energy), the corresponding power deposited in the target is <10kW, and the maximum power density in the target is equivalent to that produced in current HRIBF targets. The 10¹³ fs^-1 rate is ~25 times larger than the current HRIBF proton-induced fission rate, but since photo-fission is a much "cooler" process the yields of the most neutron-rich species are much more strongly enhanced. As an example, the yields of ^132,134,138Sn yield will be ~300, 1000, and 12000 times larger than current HRIBF capability respectively. The comparatively modest increase in total fission rate makes planning for radioactive materials handling simpler. The 10¹³ fs^-1 rate can be considered a baseline: expected improvements in target technology would lead to higher rates. Expected intensities for un-accelerated (~50 keV) beams, and for single-stripped post-accelerated beams are shown in Fig.8-1 for the baseline 10¹³ fs^-1 rate.

Figure 8-1: Expected intensities for un-accelerated (~50 keV) beams, and for single-stripped post-accelerated beams for the baseline 10¹³ fs^-1 rate.

This upgrade will provide world class neutron-rich beams, but will only impact our proton-rich capability indirectly. The chief competitors for delivery of these beams will be ISAC-2 and SPIRAL-2. ISAC-2 will begin the development of fission fragment beams after licensing issues are addressed. The timescale for this is unclear. Their 50 kW, 500-MeV proton beam incident directly on a uranium carbide target will produce ~5x10¹³ fs^-1, however yield of the most neutron rich species will be substantially less than that produced by photofission at 10¹³fs^-1. Undoubtedly, indirect targets will eventually be developed at ISAC-2 to produce cold fission with secondary neutrons; the ultimate fission rate achieved in this mode depends on geometry and target size. The goal of the ambitious SPIRAL-2 project is a fission rate of 10¹⁴ s^-1, produced by ~18 MeV neutrons from breakup of a 5 mA beam of 40-MeV deuterons. The fission rate goal will require use of very large targets (~5 kg U), with attendant uncertainties in the decay losses from short-lived beams. A more conservative target, likely to be used in early implementation will produce ~10¹³ fs^-1. Operation of SPIRAL-2 at full power levels will not occur before 2013.

In addition to the remarkable yields of neutron-rich species that can be achieved, a second driver accelerator at HRIBF will offer us the opportunity to undertake an upgrade of ORIC, which should improve our capability on the neutron deficient side of stability.
In December, technical studies and preliminary design concepts for the photo-fission upgrade were presented to the HRIBF Scientific Policy Committee. Their report was very favorable, encouraging us to proceed with development of a full proposal. Documentation of the preliminary design study can be found on the HRIBF website. It is far too early in the process to present a timeline, but it should be possible to be operational by 2012 at the latest.

9. RISAC Report From National Academies- National Research Council
(W. Nazarewicz )

The long awaited Report from the Rare Isotope Science Assessment Committee (RISAC) of the National Academies- National Research Council on "Scientific Opportunities with a Rare-Isotope Facility in the United States" is finally public. The report gives strong endorsement to the vital place of nuclear structure and astrophysics in the nuclear science portfolio of the U.S., and specifically to the science and applications of exotic nuclei and to the role of an advanced U.S. facility for rare-isotope beams (dubbed FRIB in the report) for their study in the U.S.

Specifically, the report states "that studies of nuclei and nuclear astrophysics constitute a vital component of the nuclear science portfolio in the U.S. Failure to pursue such a capability will not only lead to the forfeiture of U.S. leadership but will likely erode our current capability and curtail the training of future American nuclear scientists." The report concludes that "the U.S. should plan for, and develop the technologies for, a national facility for rare isotope science of the type embodied in the FRIB concept."
Section 3.1 of the the report gives an overview of existing rare-isotope facilities in the Americas. The description of current HRIBF capabilities and proposed upgrades can be found on p. 31. Concerning the uniqueness of the current U.S. radioactive nuclear beams program, the report states:
"The current U.S. program is world leading, with the highest intensity fast exotic beams available at the NSCL and a unique set of beams from actinide targets at HRIBF."
"Clearly, the major national user facilities in the United States (NSCL at MSU, and HRIBF at ORNL) are now competitive with the world's other leading facilities and, thus, are extremely important."
The RISAC report will provide crucial input for the 2007 NSAC long-range planning process. The long-range plan town meeting on Nuclear Astrophysics / Study of Nuclei was held January 19-21, 2007, in Chicago. The meeting was well attended and the final resolution reaffirms the priorities of the field. The program and presentations can be found on the meeting's website.

10. Joint JUSTIPEN-LACM Meeting at JIHIR to be Held on March 5-8, 2007
(W. Nazarewicz )

The Joint Institute for Heavy Ion Research (JIHIR) at Oak Ridge National Laboratory will hold the Joint JUSTIPEN-LACM Meeting on March 5-8, 2007. The meeting is a merger of two workshops: (i) the annual NNSA-JIHIR meeting on the nuclear large amplitude collective motion (LACM) with an emphasis on fission, and (ii) the US-Japan theory meeting under the auspices of the Japan-US Theory Institute for Physics with Exoctic Nuclei (JUSTIPEN).

The purpose of the meeting, jointly organized by the JUSTIPEN Governing Board and by the UT/ORNL theory group, is to bring together scientists (theorists and experimentalists) with interests in physics of radioactive nuclei, LACM, and theoretical approaches related to the SciDAC-2 UNEDF project. The emphasis of the meeting will be on topics related to future collaborations with Japanese groups (under JUSTIPEN).
There is no charge to attend the meeting, but those interested should contact Thomas Papenbrock for registration information that is needed to process entry to the laboratory. We are asking even those holding current ORNL badges to register so an accurate count can be obtained for the lunches and coffee breaks. More information about the workshop will soon be available at the workshop webpage. We are looking forward to an exciting meeting with stimulating discussions.

11. Astrophysics Workshop Held in October 2006 at HRIBF
(D. W. Bardayan )

A workshop was held October 23-24, 2006 at the ORNL Holifield Radioactive Ion Beam Facility on Nuclear Measurements for Astrophysics. The purpose of the workshop, hosted by the HRIBF users' executive committee and the Joint Institute for Heavy Ion Research, was to bring together scientists who wish to study nuclear astrophysics with radioactive beams, to acquaint participants with HRIBF's beams and experimental facilities available for such experimental studies, and to foster collaborative efforts between participants. The radioactive beams available from the HRIBF span a large range of neutron- and proton-rich isotopes at energies suitable for studies of a wide variety of important and interesting astrophysical phenomena such as novae, supernovae, and X-ray bursts.

Participation in the workshop was outstanding with approximately 75 scientists from North America and Europe attending. The presentations are available for viewing at the workshop website.

12. PAC-13 Results and PAC-14
(C.J. Gross, HRIBF Scientific Liaison)

PAC-13 met December 11-12, 2006, in Oak Ridge and considered 18 proposals and letters of intent which requested 259 shifts of radioactive beams (RIBs), 47 shifts of low intensity stable beams (SIB for RIBs), and 27 shifts of stable beams (SIBs). Of these, a total of 101 RIB shifts, 36 SIB for RIB shifts, and 27 SIB shifts were approved.
Approved experiments requested RIBs of ¹⁰Be, ¹⁸F, ⁸⁰Ge, ^86,88,90Br, ^126,130,132Sn, and ^132,134Te. The total number of accepted proposals was 10; 8 of which were from outside organizations. A letter of intent using ¹⁰Be beams was also endorsed. One proposal was withdrawn prior to the meeting.
Robert Grzywacz, chair of the Users Executive Committee, represented the Users at the meeting.
We anticipate PAC-14 to occur in late October of this year with proposals due in early September.

13. Report of the 2006 DNP Fall Meeting in Nashville
(D. Dean)

The Annual Meeting of the American Physical Society's Division of Nuclear Physics was held in Nashville at the Gaylord Opryland Hotel during 25-28 October 2006. The DNP was locally organized by ORNL staff, Jeff Blackmon, David Dean (co-chair), David Radford, Glenn Young, and Vanderbilt faculty members Victoria Greene (chair), Joe Hamilton, Charles Maguire, Volker Oberacker, A.V. Ramayya, Sait Umar, and Julia Velkovska. The meeting was well attended.

The meeting consisted of a plenary session as well as parallel, invited and contributed sessions and several minisymposia. The plenary speakers were W.A. Zajc, "Fundamental Investigations in QCD", G. Cates, "The JLab Physics Program Today and with the 12 GeV Upgrade", W.E. Ormand, "Toward a Deeper Understanding of the Nucleus with Exotic Nuclei", and S. Freedman, "How nuclear physics is helping us get beyond the Standard Model". These speakers gave forward looking talks that led into a discussion of the Long Range Plan Activities taking place in 2007.

The meeting was preceded by three workshops that were held on Wednesday, October 25. One all-day workshop was entitled Exotic nuclei: from the laboratory to the cosmos. The organizers were David Dean, Jeff Blackmon, Joe Hamilton, and Volker Oberacker. A second workshop ran parallel to the first and was entitled Properties and signatures of sQGP. The third workshop, Spin structure of the nucleon, was in the afternoon only. These latter two workshops were organized by Julia Velkovska and Charles Maguire from Vanderbilt. The DNP Business Meeting was held on Friday afternoon following the afternoon parallel sessions. Users group and other satellite meetings were held Thursday evening.

Feature Articles

RA1. RIB Development
(D. W. Stracener)

The last two RIB campaigns have utilized a different uranium carbide target and the RIB yields have been as good as or better than any previously measured from the RIB Injector. The yields of the radioactive beams accelerated in the last few months are listed in the article describing the operations of the RIB Injector.
Uranium carbide (UC) targets used at the HRIBF have been manufactured in the past by applying a thin UC coating onto the fibers of a low-density, rugged carbon matrix. These targets have been used successfully for as long as 50 days to produce high yields of fission fragments via proton-induced fission. The production beam is 54-MeV protons with an average current of 10 microAmps. However, the manufacturing process is complicated and therefore, costly and it has been difficult to consistently produce high-quality targets.
The new uranium carbide targets are fabricated from a uranyl nitrate solution mixed with graphite powders and, so far, the process seems to produce UC targets with a more consistent quality. The UC targets are manufactured at ORNL in collaboration with Jim Kiggans in the Materials Science and Technology Division. The process is simpler than the previously-used technique resulting in lower costs and more reproducible results.
Each of these new UC disks is 0.15 cm thick with a diameter of 1.5 cm and a density of 2.2 g/cm³. The RIB production target consists of 13 of these disks to achieve a target thickness of 4.2 g/cm², which is optimized for use with a 54-MeV proton beam. The UC disks are similar to pressed-powder targets used at other ISOL facilities but the fabrication process used here at ORNL is slightly different. The uranyl nitrate crystals are added to an organic binder solution and a flaky graphite mixture is added. This suspension is mixed using a Spex mill and then dried slowly at temperatures around 50 C. The graphite mixture consists of both natural graphite and synthetic graphite with particulate sizes of 6.4 micron and 33 microns, respectively. After drying, the powder is milled to make the particulate size more uniform and to break up any agglomerates. The target disks are then pressed from this powder at relatively low pressures and sintered in a vacuum furnace at temperatures around 1800 C to drive off the volatile components of the binder and to convert the uranium to uranium carbide. Further work is needed to determine the UC particulate size in the final target.
In the next few months, we plan to investigate RIB release efficiencies and useful lifetimes of these targets as a function of target density, UC particulate size, uranium to carbon ratio, and the characteristics of the graphite used in the fabrication process.

RA2. Accelerator System Status

ORIC Operations and Development (B. A. Tatum)

Extensive upgrades to the ORIC rf system were reported in the last edition of this newsletter. This effort appears to have paid off. ORIC operated with proton beam on target for RIB production for more than 1500 hours over a six month period from June 1 though the end of November. Over 700 of those hours were recorded in October and November. A scheduled maintenance period began in December. Unfortunately, an HPTL development run scheduled for December was delayed due to bearing failure on the main field MG set. The bearing was repaired and the MG set is back in service. Two week-long HPTL runs with collaborators from Legnaro will take place in January. Otherwise, ORIC will be shut down until February 12 when tandem maintenance is scheduled for completion.
As for the rf system, we are now running routinely, and reliably, with two 500-watt AR Kalmus rf amplifiers and two Werlatone commercial combiner/divider units. The tunable, ceramic-envelope plate capacitors that were also installed last year have operated flawlessly. Thanks to the Facilities and Operations Directorate, our battery bank that is needed for emergency lighting and starting the main field MG set has been totally replaced. Twenty new 6 Vdc batteries and a seismic rack system have been installed. F&O also funded a new vacuum breaker for the 13.8kV switchgear that is required for starting the MG-set. It has been received and is slated for installation in January.

RIB Injector Operations and Development (P.E. Mueller)

During the period from 1 July 2006 to 31 December 2006, the 25 MV Tandem Electrostatic Accelerator delivered beams of
200 kpps [24.6 MV 16+/29+ terminal foil / high energy foil stripped] 630 MeV 99% ¹³⁰Sn,
90 kpps [24.6 MV 16+/29+ terminal foil / high energy foil stripped] 630 MeV 95% ¹³²Sn, and
330 kpps [24.1 MV 17+/30+ terminal foil / high energy foil stripped] 643 MeV ¹³⁴Te to the astrophysics endstation in Beam Line 41, and
280 pps [17.5 MV 12+ terminal foil stripped] 228 MeV ⁷⁶Cu,
30 pps [17.3 MV 12+ terminal foil stripped] 225 MeV ⁷⁷Cu,
3 pps [17.1 MV 12+ terminal foil stripped] 221 MeV ⁷⁸Cu,
0.13 pps [19.8 MV 11+ terminal foil stripped] 237 MeV ⁷⁹Cu,
60 pps [16.0 MV 12+ terminal foil stripped] 209 MeV ⁸³Ga,
2.7 pps [15.9 MV 12+ terminal foil stripped] 206 MeV ⁸⁴Ga, and
0.1 pps [15.9 MV 12+ terminal foil stripped] 206 MeV ⁸⁵Ga to the decay spectroscopy endstation in Beam Line 21.
These beams were produced via proton induced fission of ²³⁸U by bombarding a pressed powder uranium carbide target coupled to an Electron Beam Plasma (positive) Ion Source (EBPIS) with 8 - 12 uA of 54 MeV ¹H. Additionally, the high purity tin beams were produced by passing a positive tin sulfide beam through the recirculating cesium jet charge exchange cell and selecting the negative tin beam resulting from molecular breakup.

Tandem Operations and Development (M. Meigs)

The Tandem Accelerator was operated for almost 3000 hours since the last report. The machine ran at terminal potentials of 9.97 to 24.6 MV and the stable beams ¹H, ³²S, ⁴⁸Ti, ^54,56Fe, ⁵⁸Ni, ^70,72,76Ge, ^76,78,80,82Se, ⁹⁸Mo, ¹⁰⁷Ag, ^118,124Sn, ^{122,124,125,126,130}Te and ²³⁸U were provided, with Mo being accelerated in the Tandem for the first time. ²³⁸U was provided from the RIB injector uranium carbide source and proved easier to tune than previous tries with the stable injector. Radioactive beams of ^76,77,78,79Cu, ^83,84,85Ga, ^132,134Sn, and ¹³⁴Te accounted for more than 1000 hours of beam on target. Deconditioning after some sparks required about 50 hours of conditioning. The affected units were examined carefully when the tank was opened for maintenance on December 5, and a thorough leak check was done, but no cause was found. In any case, the deconditioning phenomenon was observed after only a small fraction of sparks. The tank remains open and will probably be closed about the 1^st of February. The Tandem Accelerator has run for almost a year without having to open for maintenance...a record!

The highlight of this reporting period was that the accelerator ran for weeks on end above 24 MV with relatively little trouble. This high voltage operation was helped by the new gas handling procedure which allowed the accelerator tank to be filled to a higher SF₆ pressure. A shipment of SF₆ should arrive in a month or so and we can try for even higher voltages.

RA3. Experimental Equipment/Technique - A Novel Approach for Measurement of (p,α) Reactions
(J.C. Blackmon, Spokesperson)

We have developed a new technique for measurements of low energy (p,α) reactions. The approach uses a differentially pumped windowless gas target and is optimized for studies of narrow resonances using radioactive ion beams. We have demonstrated this new approach by applying it to measure a recently reported resonance in the ¹⁷O(p,α)¹⁴N reaction at E_cm=183 keV [CHA05] that is important for understanding nucleosynthesis in giant stars and novae. In this article we briefly summarize the technique, the results from the ¹⁷O(p,α)¹⁴N measurement, and plans for future measurements using the technique with radioactive ion beams.
In our demonstration experiment, beams of ¹⁷O from the HRIBF tandem accelerator bombarded a large scattering chamber filled with hydrogen gas at a pressure of 4 Torr. The scattering chamber was connected to the accelerator beamline by a series of 4 differentially-pumped chambers separated by 5-mm diameter apertures. A schematic illustration of the experimental setup is shown in Fig. RA3-1. No windows or foils obstructed the beam or contained the gas, and the hydrogen gas in the scattering chamber served as a spatially extended target for the (p,α) reaction. Ultra-high purity gas was used in a single-pass system, and the differential pumping stages reduced the pressure to about 10^-7Torr over a distance of less than half a meter.

Figure RA3-1: Schematic of the experimental setup. Only 2 of the 4 differential pumping chambers are shown.

The α and ¹⁴N reaction products were detected in coincidence by an array of silicon strip detectors operating within the hydrogen gas environment. Α particles were detected by the SIDAR array, while recoiling ¹⁴N (emitted at angles less than 21 degrees) were detected by a CD-style detector (Micron semiconductor Type S1 detector) mounted just downstream of SIDAR. The kinematics and relative timing of the two detected particles allowed the ¹⁷O(p,α)¹⁴N reaction to be cleanly distinguished. The energies of particles detected by the S1 detector are plotted against the energy of the coincident particle detected by SIDAR in Fig. RA3-2 for events that are coincident within 0.4 microseconds. Events from the ¹⁷O(p,α)¹⁴N reaction are distinguished as a straight line with a constant sum energy indicative of the reaction Q value and independent of the reaction angle.

Figure RA3-2: The energy of particles detected in the CD (S1) detector is plotted versus the energy of coincident particles in SIDAR for (a) E(¹⁷O)=3.29 MeV and (b) E(¹⁷O)=3.34 MeV. Any bins with at least 1 count have a uniform black fill. The incident beam on target is comparable for both (a) and (b).

Each segment of the detector array views reaction products from a wide range of angles depending on the point of origin along the beam axis. However, the reaction angle of each ¹⁷O(p,α)¹⁴N event can be determined from the measured α energy, which varies rapidly with angle. We found all of the ¹⁷O(p,α)¹⁴N events to originate from a narrow range of positions within the target chamber, indicating that the entire yield is due to a narrow resonance. The centroid of the reaction vertex was found to vary linearly with the incident energy, allowing the stopping power for oxygen ions in hydrogen gas near the peak of the Bragg curve (E(¹⁷O)=193 keV/u) to be determined for the first time. Our experimental result, (63�1)x10^-15eV/cm² is in good agreement with popular semi-empirical models [ZIE03,PAU03].
The integrated beam current at each energy was determined by normalizing to ¹²C(¹⁷O,¹⁷O)¹²C elastic scattering measured simultaneously with the ¹⁷O(p,α)¹⁴N reaction using a carbon foil and two single-collimated silicon surface barrier detectors. The dominant systematic uncertainty results from the thickness of this carbon foil used for beam current normalization, which was determined in separate measurements to a precision of 6%.

The thick target yield curve is shown in Fig. RA3-3 along with a best fit to the data, which results in a resonance strength of 1.70�0.15 meV including both statistical and systematic uncertainties added in quadrature. We also measured a yield curve at a target pressure of 1 Torr with consistent (but less precise) results. Our result is in good agreement with the recent first measurement of this resonance strength (1.6�0.2 meV) using a high-intensity, low-energy proton beam [CHA05]. We also determined the resonance energy to a precision of about 0.3%, with a value also in good agreement with Ref. [CHA05].

Figure RA3-3: Measured yield as a function of the incident ¹⁷O energy. Triangles represent upper limits. The curve is a best-fit to the data.

Our new approach to (p,α) reactions was designed for high sensitivity for narrow resonances using radioactive ion beams. The pure nature of the target increases the reaction yield by about a factor of 3 over that from polypropylene targets, and the gas pressure can be adjusted to match the expected resonance width, decreasing the yield from non-resonant and background sources. We believe this technique is also well suited to measurements of (α,p) reactions using helium gas. We next plan to apply this technique to measure the strength of low-energy resonances in the ¹⁸F(p,α)¹⁵O reaction (Moazen et al., RIB-165) that are important for understanding 511-keV gamma-ray production in novae.
[CHA05] A. Chafa et al., Phys. Rev. Lett. 95 (2005) 931101; 96 (2006) 019902.
[ZIE03] J. F. Ziegler, SRIM-2003.10 (2003); see http://www.srim.org.
[PAU03] H. Paul and A. Schinner, At. Data Nucl. Data Tables 85 (2003) 377.

RA4. User Group News

The Users Executive Committee election was held in Fall 2006 and Art Champagne (UNC) and Alfredo Galindo-Uribarri (ORNL) were selected for four-year terms and join continuing members Robert Grzywacz (UT) and Walt Loveland (OSU). The committee will hold a telephone conference call soon to elect this year's chairperson and begin to organize the next users workshop. We thank Uwe Greife (Co. Mines) and David Radford (ORNL) for their service these past several years.
The HRIBF Users Group met on October 26, 2006 in Nashville at the Fall Meeting of the DNP. More than 110 people attended the meeting which was be held jointly with the ATLAS, NSCL, GAMMASPHERE/GRETINA, and RIA Users groups and sponsored by HRIBF, ATLAS, and NSCL. Our portion was hosted by UEC member Uwe Greife. Carl Gross presented a facility update, Kate Grzywacz-Jones (UT) presented recent data taken on ¹³²Sn(d,p) in inverse kinematics, and Jim Beene presented our plans to upgrade the facility including an electron driver to produce intense beams of neutron-rich isotopes from fission of uranium.

RA5. Suggestions Welcome for New Beam Development

HRIBF welcomes suggestions for future radioactive beam development. Such suggestions may take the form of a Letter of Intent or an e-mail to the Liaison Officer at grosscj@ornl.gov. In any case, a brief description of the physics to be addressed with the proposed beam should be included. Of course, any ideas on specific target material, production rates, and/or the chemistry involved are also welcome but not necessary. In many cases, we should have some idea of the scope of the problems involved.
Beam suggestions should be within the relevant facility parameters/capabilities listed below.

The tandem accelerates negative ions only.
Positive ions may be charge-exchanged or used directly off the platform (E < 40 keV).
ORIC presently produces up to 52-MeV of ¹H (12 uA); 49-MeV ²H (12 uA); 120-MeV ³He (not yet attempted, costly); 100-MeV ⁴He (3 uA). Higher currents may be possible.
Typical reactions required to produce more than 10⁶ ions per second are n, 2n, pn, and alpha-n fusion-evaporation reaction channels and beam-induced fission products. More exotic reactions are possible if extremely low beam currents are all that is needed.
Species release is strongly related to the chemistry between the target material and the beam species. It is best when the properties are different and the target is refractory. Thin, robust targets (fibrous, liquid metals, a few grams per square centimeter) must be able to withstand 1500 degrees Celsius or more.
Minimum half-life is seconds unless chemistry is very favorable.
Very long-lived species (T_1/2 > 1 h) are probably best done in batchmode, i.e., radioactive species are produced with ORIC beams and then transported to the ion source where beams are produced via sputtering. Sputter rates of the species and target substrates are important.
Isobaric separation is possible for light beams (fully stripped ions), while isobaric enhancement may be possible for heavy beams.
Beware of long-lived daughters or contaminant reaction channels.

RA6. HRIBF Experiments, July through December 2006
(M. R. Lay)

Date Exp. No. Spokesperson Title of Experiment

7/1-4 Shutdown

7/5-6 RIB-035 Stracener/ORNL Target ion source development (actinide targets)

7/7 RIB-132 Jones/University of Tennessee Study of the single-particle structure of 133Sn via the 132Sn(d,p) reaction in inverse kinematics

7/8-9 Shutdown

7/10-15 RIB-134 Kozub/Tennessee Tech The 130Sn(d,p)131Sn reaction in inverse kinematics

7/16 Shutdown

7/17-21 RIB-035 Stracener/ORNL Target ion source development (actinide targets)

7/22-23 Shutdown

7/24-25 RIB-082 Gross/ORNL A time-of-flight system for measuring fusion-evaporation cross-sections using radioactive ion beams

7/25 Shutdown

7/26 RIB-082 Gross/ORNL A time-of-flight system for measuring fusion-evaporation cross-sections using radioactive ion beams

7/27 RIB-134 Kozub/Tennessee Tech The 130Sn(d,p)131Sn reaction in inverse kinematics

7/27-30 Shutdown

7/31-8/2 RIB-101 Page/University of Liverpool Search for new alpha emitters above 100Sn

8/3 RIB-132 Jones/University of Tennessee Study of the single-particle structure of 133Sn via the 132Sn(d,p) reaction in inverse kinematics

8/3-4 RIB-101 Page/University of Liverpool Search for new alpha emitters above 100Sn

8/5-6 Shutdown

8/7-9/8 RIB-132 Jones/University of Tennessee Study of the single-particle structure of 133Sn via the 132Sn(d,p) reaction in inverse kinematics

9/8 RIB-014 Stracener/ORNL Target ion source development (As & F)

9/9-10 Shutdown

9/11-12 RIB-014 Stracener/ORNL Target ion source development (As & F)

9/13-18 RIB-132 Jones/University of Tennessee Study of the single-particle structure of 133Sn via the 132Sn(d,p) reaction in inverse kinematics

9/19-23 RIB-148 Stuchbery/Australian National University Gyromagnetic ratios in 134Te and 136Te by the Recoil in Vacuum Technique

9/24-28 RIB-132 Jones/University of Tennessee Study of the single-particle structure of 133Sn via the 132Sn(d,p) reaction in inverse kinematics

9/28-29 RIB-148 Stuchbery/Australian National University Gyromagnetic ratios in 134Te and 136Te by the Recoil in Vacuum Technique

9/29-30 RIB-082 Gross/ORNL A time-of-flight system for measuring fusion-evaporation cross-sections using radioactive ion beams

10/1-2 Shutdown

10/2-6 RIB-082 Gross/ORNL A time-of-flight system for measuring fusion-evaporation cross-sections using radioactive ion beams

10/7-8 Shutdown

10/9-10 RIB-082 Gross/ORNL A time-of-flight system for measuring fusion-evaporation cross-sections using radioactive ion beams

10/11-13 RIB-148 Stuchbery/Australian National University Gyromagnetic ratios in 134Te and 136Te by the Recoil in Vacuum Technique

10/14-15 Shutdown

10/16-19 RIB-148 Stuchbery/Australian National University Gyromagnetic ratios in 134Te and 136Te by the Recoil in Vacuum Technique

10/19-20 RIB-014 Stracener/ORNL Target ion source development (As & F)

10/20-25 RIB-132 Jones/University of Tennessee Study of the single-particle structure of 133Sn via the 132Sn(d,p) reaction in inverse kinematics

10/25-11/3 RIB-134 Kozub/Tennessee Tech The 130Sn(d,p)131Sn reaction in inverse kinematics

11/3-6 RIB-136 Forster/University of Montreal Lifetimes of Very Heavy Compound Nuclei Preceding Heavy-Ion Induced Fission

11/7-13 RIB-122 Winger/Mississippi State University Structure of neutron-rich nuclei near 78Ni studied via beta-decay of postaccelerated Cu beams

11/13-15 RIB-121 Shapira/ORNL Subbarrier fusion of 134Sn with 64Ni

11/15-17 RIB-039 Mueller/ORNL High voltage injector development

11/17-22 RIB-122 Winger/Mississippi State University Structure of neutron-rich nuclei near 78Ni studied via beta-decay of postaccelerated Cu beams

11/23-26 Shutdown

11/27-12/5 RIB-132 Jones/University of Tennessee Study of the single-particle structure of 133Sn via the 132Sn(d,p) reaction in inverse kinematics

12/5-31 Shutdown