HRIBF NEWS


Edition 8, No. 1 Winter Quarter 2000 Price: FREE

Contents:

Feature Articles Regular Articles

Editor: Carl J. Gross

Feature contributors: J. R. Beene, F. E. Bertrand, T. N. Ginter, R. Grzywacz, W. Nazarewicz,
Regular contributors: F. P. Ervin, C. J. Gross, M. J. Meigs, W. Nazarewicz, D. W. Stracener, B. A. Tatum, R. F. Welton


1. Update of RIB Delivery Plans

The HRIBF is coming to the end of a remarkably successful year-long campaign of 17,18F experiments. This success is based on a series of innovative developments in targetry and ion sources which have been detailed in past issues of this newsletter. We have completed six experiments plus several test and discretionary runs. We have provided almost 2000 hours of fluorine RIB on target for experiments, with accelerated beam intensities of up to 10**7 17F ions/s in a cocktail beam (17O:17F::2:1), and up to 3x10**6 ions/s of pure 17F. About 900 hours of beam on target have been provided since mid-December 1999. In the last week we have developed a 18F beam using the 16O(4He,pn)18F production reaction, using the same target and ion source system developed for 17F.

The first fluorine RIB experiment, a study of 17F(p,p) which was completed early last year, was able to locate and measure the properties of a long-sought and astrophysically important 3+ resonance in 18Ne. This result has been published (Phys. Rev. Lett. 83, 45 (1999)), featured on the APS Physical Review Focus website (July 9, 1999) and discussed in an article in the October 1, 1999 issue of Science (286, pp. 28-31). More recently, the ORNL astrophysics group and their collaborators, in a two-month-long run, collected an impressive data set on the 17F(p,alpha) excitation function, spanning the entire range of astrophysical interest with data of truly unprecedented quality. A search for di-proton decay from states in 18Ne populated by 17F+p was just completed. While the analysis of this data is still in a very preliminary state, the results look promising. We may have finally observed this long-sought decay mode. Finally, an experiment designed to explore low-energy resonances in 18F(p,p) and 18F(p,alpha) is still under way.

From the point of view of HRIBF operations, this fluorine campaign has been a tremendous success. Two aspects that have been particularly gratifying are the performance of ORIC and the remarkable robustness and resiliency of the ORNL-developed kinetic ejection negative ion source (KENIS). The HRIBF depends on ORIC, an almost 40-year-old cyclotron, to produce radioactive species for acceleration. When we began operation as a RIB facility at the beginning of 1997, ORIC had not been depended on for day-to-day operation since the late 1970s. Getting it into the condition required to serve as a RIB driver has been an enormous effort under trying conditions. The engineering and operations staff deserve great credit. Our concentration on ORIC has clearly begun to pay dividends. ORIC has run remarkably well for the past year, but for the past three months, since a late fall shutdown for replacement of another of the many old and unreliable power supplies, the operation has been almost flawless. Our negative fluorine ion source has also been a remarkable performer. Since the first of these sources was installed on the platform in the spring of 1999, we have delivered more than 1500 hours of radioactive fluorine beam to experiments. (We delivered another 400 hours using a different target-ion source system earlier in FY1999). The latest KENIS started on-line operation in December 1999 and has since logged ~1000 hours of driver beam bombardment at an average deuteron beam current of 3 uA. It is still going strong, but now under 4He bombardment.

Though we plan to return to 17,18F experiments at a later date, we will now turn our attention to other physics-driven beams. At the HRIBF, neutron-rich RIBs can only be produced effectively by fission in actinide targets. Until very recently, safety regulations prevented us from using actinide targets in high-intensity production beams. Nevertheless, we devoted considerable effort, including extensive testing with low-intensity driver beams, to development and optimization of uranium carbide targets for neutron-rich RIB production. We will begin using this target system in high-intensity production beams in April 2000. We have also developed and tested a target and ion source system for 56Ni production. During the initial testing of the batch-mode source, a 11C beam with an intensity of about 10**6 ions/s will be produced, and will be made available for experiments for a limited time. We expect to spend the summer of 2000 running 56Ni beam experiments. Our first RIB production efforts were centered on a liquid germanium target system, which, with some additional development, is capable of producing 68,69,70As, 65,66,67Ga, and 71,72Se at reasonable intensities if demand for these beams warrants the effort. Our near-future efforts in proton-rich beam development will be concentrated on 25Al, 33,34Cl, 30,31S, and 58Cu.

2. Recent HRIBF Research - Observation of Multiple Proton Decay Branches in 146Tm

The observation [1] of fine structure in the proton decay of 131Eu recently generated excitement in the world of proton emission studies. Proton branches to the low-lying 2+ state and to the 0+ ground state of the even-even deformed nucleus 130Sm were observed. From this work it was possible to extract information on the structure of the proton-emitting state [2], as well as on the quadrupole deformation of the daughter nucleus.

In a recent HRIBF experiment on the proton emission from states in odd-odd 146Tm, we have obtained evidence for a new case of proton decay fine structure with proton transitions to neutron-excited levels in the odd-N nucleus 145Er. Our re-investigation of 146Tm decay was motivated both by the experimental systematics of low-lying levels in less exotic even-Z, odd-N nuclei near 145Er and by the results of calculations following the macroscopic-microscopic model presented in Ref. [3]. The proximity of the magic N=82 neutron shell, as well as previous results on the proton emission, suggest a spherical shape for 146Tm. However, both the experimental systematics and the calculations indicate that the excited neutron single-particle states in 145Er are expected to lie at low excitation energies (within about 200 keV), thus making the population of such states by proton emission energetically feasible. We also wanted to search for new short-lived proton-emitting states in 146Tm with half-lives below 100 microseconds. The HRIBF Double-sided Silicon Strip Detector (DSSD) setup at the Recoil Mass Spectrometer has proven to be quite effective at studying proton activities with half-lives down to a few microseconds [4-7].

Ions of 146Tm were produced in the p3n reaction of a 292-MeV 58Ni beam on a 92Mo target with a thickness of 0.91 mg/cm**2. The Recoil Mass Spectrometer was run in the converging mode to deliver charge states 26+ and 27+ of mass 146 recoils for implantation into the DSSD placed behind a position-sensitive avalanche counter (PSAC) at the spectrometer focal plane. Collimators were positioned in front of the PSAC to minimize the implantation into the DSSD of masses other than 146. The DSSD system provides 1600 pixels for detecting the energy and time of a recoil implantation event and the energy and time of the implanted recoil's decay by alpha or proton emission. Whether or not a DSSD event is observed in coincidence with the PSAC determines whether the event arises from the implantation of an ion or from a decay.

In a previous study of 146Tm [8] two proton-emitting states had been identified: one at 1.12 MeV with a half-life of 230 ms and the other at 1.19 MeV with a half-life of 70 ms. In the HRIBF experiment, although we found no new short-lived proton-emitting states, we did observe three new proton-emitting transitions at ~0.89, ~0.93, and ~1.02 MeV. A preliminary analysis of the data indicates that the new transitions at 0.89 and 0.93 MeV have a half-life consistent with that of the previously observed transition at 1.19 MeV and that the half-life of the new 1.02 MeV transition is consistent with that of the 1.12 MeV transition. The data thus supports the exciting interpretation of proton decays to excited states in an odd-N spherical nucleus. Surprisingly, we can thus probe exotic NEUTRON states via PROTON radioactivity studies. Also, we can study the effects of the proton-neutron interaction on level mixing in the odd-odd proton-emitting parent.

This work is being carried out by a collaboration of researchers from Vanderbilt University, UNIRIB, Oak Ridge National Laboratory, ORISE, the University of Tennessee, Warsaw University, Louisiana State University, and the University of Maryland.

References

[1] A. A. Sonzogni et al., Phys. Rev. Lett. 83, 1116 (1999).
[2] A. T. Kruppa, B. Barmore, W. Nazarewicz, and T. Vertse, submitted to Phys. Rev. Lett.
[3] W. Nazarewicz, M. A. Riley, and J. D. Garrett, Nucl. Phys. A 512, 61 (1990).
[4] J. C. Batchelder et al., Phys. Rev. C 57, R1042 (1998).
[5] C. R. Bingham et al., Phys. Rev. C 59, R2984 (1999).
[6] K. Rykaczewski et al., Phys. Rev. C 60, 011301 (1999).
[7] T. N. Ginter et al., Phys Rev. C 61, 014308 (1999).
[8] K. Livingston et al., Phys. Lett. B 312, 46 (1993).

3. Recent HRIBF Research - Selective Study of the Excited States of the N=Z Nucleus 66As using the Isomer Decay Tagging Technique

A collaboration involving the University of Tennessee, Warsaw University, ORNL, Lousiana State University, Vanderbilt University and the University of Maryland has identified several new prompt electromagnetic transitions in the N=Z nucleus 66As for the first time. These gamma lines depopulate the discrete yrast levels above the 17 us, 3024 keV isomeric state discovered in a fragmentation-type experiment [1]. Very clear, but limited, information obtained in the study of the isomeric decay of this odd-odd nucleus allowed us to make some guesses on the underlying nuclear structure with the help of empirical rules and systematics. Clearly, this non-defomed midshell nucleus is a formidable problem for shell-model calculations, which need to involve f5/2, p3/2, p1/2 and also the g9/2 orbitals to reliably predict its properties. Such calculations are conceivable with modern shell-model codes [2], and such calculations have been made for the neighboring odd-odd N=Z nucleus 62Ga [3].

In parallel to the further study of isomeric decay, we undertook an effort to identify prompt gammas above the known isomer to extend the empirical knowledge on this system as much as technically possible. The experiment was enabled by using the technique of Isomer Decay Tagging (IDT) for the selection of the reaction channel. It is the variation of the well-established Recoil Decay Tagging (RDT) technique [4] which uses the characteristic particle (proton, alpha) radioactive decay of the nucleus to identify in-beam gamma radiation. The RDT technique has been previously used at HRIBF for the studies of 113Cs [5] and 151Lu [6]. The IDT technique uses the gamma radiation from the decay of isomeric states detected after the recoil spectrometer to tag the radiation emitted near the production target. This method has already been applied by Cullen et al. [7] to assign the states in 138Gd. This is, however, the first time we have used this method to identify unknown excited states. Our experiment utilized the Recoil Mass Spectrometer (RMS) [8] and an 80-MeV 28Si beam on a 1 mg/cm**2 40Ca target sandwiched between two thin gold layers. The IDT technique requires two gamma-ray detection stations. For the prompt radiation, the ORNL Clarion array was used; for this experiment, it consisted of nine clover detectors, five of them Compton-suppressed. The Clarion efficiency was about 2% at 1.3 MeV. The isomer detection station consisted of a germanium clover detector placed just inside an 8-fold segmented BGO detector, which is normally used as a Compton-suppressor. The active ion catcher, a square silicon detector, was placed inside the BGO very close to the front of the clover detector. In this geometry the BGO+Clover setup covers nearly full solid angle for the detection of the isomeric radiation and provided nearly 100% isomer tagging efficiency, due to the fact that each isomer decay is followed by five different gamma rays. Compared to the RDT technique, high gamma multiplicity counterbalances much smaller gamma detection efficiency for detection of one transition. The BGO detector's resolution was sufficient to distinguish between high energy lines of 394, 837, and 1552 keV belonging to the 66As isomeric decay but not between 115- and 125-keV isomeric transitions. Thus, instead of using discrete lines, all BGO-detected gammas, including Compton-scattered, were used for tagging purposes. Since this detector was not shielded from the natural background radiation, a substantial contribution from random correlations reduced the quality of the tagging, but this effect has been controlled. The unambiguous assignment of prompt gamma rays to 66As was done with discrete isomeric lines observed in the final focus clover. The total BGO efficiency was about 4 times larger than the total clover efficiency for the detection of any 66mAs decay and helped establish gamma-gamma coincidences and angular asymmetries. The RMS was tuned in converging ion mode to transmit recoils with mass 66; for the chosen reaction, only As and Ge isotopes produced. A Position Sensitive Avalanche Counter (PSAC) was placed in a mass dispersive plane about 1 meter upstream from the ion catcher. Vertical slits to block the unwanted ions from the strong reaction channels like 65Ga and 62Zn were placed in front of the PSAC in order to implant only A=66 recoils. The use of slits was crucial for the experiment and only a small contribution from other ions arrived at the RMS final focus. The time of flight of the A=66 ions through the spectrometer was about 3.5 us. The main role of the gas detector was to provide a time signal for each arriving ion to correlate in-beam and isomeric gammas. This signal was used to generate a 32-us gate for the detection of isomeric gammas at the RMS final focus and a trigger and gate for Clarion-detected prompt radiation.

The observed gamma rays have energies between 720 to 2100 keV and do not exhibit any obvious rotational structure, thus proving the spherical shell-model nature of the yrast levels. We also identified a new isomeric transition from a state with a lifetime of a few nanoseconds. This transition, most probably of M2 type, requires a parity change, and thus the g9/2 orbital has to be involved in the wave function of this state. No gammas have been found to feed directly the 1356 keV isomer. Shell-model calculations which incorporate the g9/2 orbitals are in progress. Further investigation of the data and their relation to T=0 pairing questions are continuing.

References

[1] R. Grzywacz et al., Phys. Lett. B 429 (1998) 247.
[2] E. Caurier, code ANTOINE (1989).
[3] S. M. Vincent et al., Phys. Lett. B 437 (1998) 264.
[4] R. S. Simon et al., Z. Phys. A 325 (1986) 197; E. S. Paul et al., Phys. Rev. C 51 (1995) 78
[5] C. J. Gross et al., ENAM 1998 Bellaire, Michigan, p. 444.
[6] C.-H. Yu et al., Phys. Rev. C 58 (1998) R3042.
[7] D. Cullen et al., Phys. Rev. C 58 (1998) 58.
[8] C. J. Gross et al., NIM A, in press.

4. Electronic Submission of Proposals Coming Soon

Due to the successful 17F series of experiments, our plans to issue the next Call for Proposals has been delayed. We hope to issue the Call within the next two months. We still intend to demonstrate actual neutron-rich RIB intensities delivered on target prior to issuing the Call. Although focused on neutron-rich beams, we will accept additional requests to use our other RIBs: 11C, 17,18F, 56Ni, 56Co, 66,67Ga, 69,70As, and 71,72Se.

We have decided to implement electronic submission of proposals for the next PAC. We will accept the four-page proposals as email attachments in either Portable Data Format (pdf) or Postscript Format (ps). We prefer pdf since it uses compression techniques which can typically lower the size of the file by up to a factor of 10. More details may be found soon on our website at http://www.phy.ornl.gov/hribf/users/prop_exp_elec.html.

5. Outside User Policy Statement

We realize that our single-minded insistence on giving priority to radioactive ion beam runs whenever radioactive beam is available has made carrying out approved stable ion beam experiments very difficult for outside users. Nevertheless, we believe it was a necessary interim policy that helped get the HRIBF off the ground as a RIB facility. We now intend to define short periods of fixed-schedule operation during which outside user experiments will be scheduled with fixed start dates (within one or two days). The fixed-schedule periods are intended primarily to accommodate outside users for whom a sudden schedule change would result in added expense or significant inconvenience. Outside these special fixed-schedule periods we will continue to operate as in the past, with stable ion beam experiments scheduled on shorter notice when RIBs are not available. The first such fixed-schedule period will be late this summer and will be announced shortly.

Please remember that the basic mission of HRIBF continues to be physics with radioactive beams. The limited conditions under which stable ion beam experiments are considered appropriate for HRIBF remain unchanged. Only the scheduling system will be modified to better accommodate our user community.

6. Holifield to Celebrate 20-Year Anniversary

To celebrate twenty years of science at the Holifield facility, we are organizing an international conference "ISOL'01" on March 11-14, 2001, in Oak Ridge, Tennessee. The conference will focus on nuclear physics studies with radioactive ion beams at ISOL facilities, with emphasis on nuclear structure, nuclear reactions, nuclear astrophysics, and fundamental interactions.

More details about the conference will be announced in May. If you did not receive a similar announcement in December and you would like to be added to the mailing list, please send an email to isol01@mail.phy.ornl.gov. Please reserve March 11-14, 2001, on your calendar.

7. Tests of the CLARION and HyBall Arrays with the Recoil Mass Spectrometer (CHARMS)

The CHARMS system - CLARION and HyBall Arrays with the Recoil Mass Spectrometer - is presently undergoing tests. In several initial test runs using 16O + 12C, 17F + 12C, 58Ni + 58Ni, and 40Ca + 92Mo, the various components of CHARMS have been successfully tested together. Different triggers have been tested including CLARION+HyBall (CHA) and CLARION+HyBall+RMS (CHARMS). Charged-particle, mass-gated, gamma-ray spectra have been taken, and the data shows high sensitivity to mass and isotope selection. More details will follow in the next newsletter and on our web site in time for the next Call for Proposals.

RA1 - RIB Development

Neutron-rich RIB Development
Preparation of the target/ion source for the production of neutron-rich beams is nearing completion. The tests performed at UNISOR with the uranium carbide target indicate that the highest yields for negatively charged ions of Sn and Br isotopes are achieved using the positive ion source followed by a charge exchange cell rather than using the ion source which produces negative ions directly. The standard HRIBF EBP ion source and TIS enclosure will be used for this production run which is the first time this target has been used on the RIB platform. The target consists of nine 2-mm-thick disks of a rigid matrix of glassy carbon fibers (approx. 60-micron diameter) that have been coated with a 12-micron layer of uranium carbide. This target will operate at a temperature of about 2000 C. The radioactive species are produced via proton-induced fission using a 42-MeV proton beam from ORIC. The cross section for fission drops rapidly below 15 MeV so the target thickness is designed to allow the proton beam to exit the target and stop in a graphite beam dump. This reduces the beam power deposited in the target. The beam dump is electrically isolated and will be used to monitor the ORIC beam current.

UNISOR Facility - Charge Exchange Cell
Initial tests of the new charge exchange cell have begun at UNISOR. Negatively charged ions of Sn isotopes have been produced with an efficiency of 35%, which is close to the values reported in the literature. We are still trying to determine the best operating parameters with respect to charge exchange efficiency, beam scattering, and the cesium depletion rate. Tests are continuing to optimize the cell for 40-keV beams of Sn, Br, and Rb isotopes. A second cell of this design has been assembled and is ready to use on the RIB Platform for the upcoming high-intensity tests with a uranium carbide target.

RA2 - Accelerator Systems Status

ORIC Operations and Development

ORIC has operated almost flawlessly during the period, providing up to 6 microamps of 44.5-MeV deuterons to the RIB Injector for 17F production. The ORIC ion source achieved a record of 768 hours of operation with a single set of cathodes from July 1999 until mid-January 2000. Previously, 300 hours had been the upper limit. The increased lifetime is a direct result of last summer's redesign of the high-voltage rod tips and cathode mounts. A new set of cathodes installed in January has already reached 450 hours of service. Due to the rigorous operational schedule, few machine upgrades have taken place. However, the rf system trimmer capacitance and power amplifier plate capacitance servos were rebuilt and have greatly contributed to more stable operation. Three new power supplies for the number two harmonic coils, unused in recent years, have been installed to restore original machine capability and flexibility in providing a wider range of light-ion beams. During the next shutdown, three additional new trim coil power supplies will be installed along with enhanced thermal protection of the coaxial extraction channel.

Tandem Operations and Development

During the period since the last report, the tandem accelerator has provided 651 hours of beam on target of which 517 hours were 17F. A larger amount of tuning time is necessary for the radioactive beams since an analog beam must first be tuned and then final tuning must be done with very low-intensity diagnostics. Two tank openings were required during this time; the first to remove an obstruction in the beam path at the terminal and the second to remove a broken shorting rod. The obstruction in the beam path was a titanium flake that had slid across a portion of the beam tube. Since the vacuum system had to be opened to remove this flake, it was necessary to condition the machine. Approximately 135 hours were spent conditioning the machine after this first tank opening with a goal of being able to operate up to 21.5 MV. The second tank opening lasted less than two days, and the terminal was at 21.23 MV for an experimental run less than ten hours after the tank had been filled with gas. The range of terminal potentials during this period was 2.55 to 21.23 MV.

RIB Injector Operations and Development

Over the winter quarter of 2000, the RIB injector has been nearly continuously providing RIBs of 17F for various HRIBF experiments. In earlier investigations, we have shown that Al17F+ yields from a positive ion source and a HfO2 target could be greatly enhanced by feeding stable Al into the source. A nearly two-order-of-magnitude improvement in the yield was observed. These experiments suggested that Al17F+ was not limited by production or diffusion of the radioactive species through the target material, but was instead limited by the availability of a carrier species. Unfortunately, the emittance growth of Al17F+ ions through the charge exchange cell precludes use of the positive source, and we must employ a negative ion source for this beam. Earlier experiments have also shown that the negative source requires the addition of Al2O3 rather than Al to achieve significant 17F- yields. These experiments suggested that a logical next step would be to try a much larger quantity of Al2O3 reactant in a negative ion source with HfO2 target material.

In late November, a negative ion source was mounted on the RIB injector along with a target which consisted of four separated rolls of HfO2 fibers spaced by a few millimeter gap and surrounded by a liner of Al2O3 felt. Initially, ~2uA of ORIC beam was applied to the target which provided ~10**5 17F ions/s from the ion source for an elapsed period of about 1 month. According to calculations, over the course of this month, approximately one-half of the Al2O3 liner should have evaporated. In early January, the yield grew and stabilized at approximately 1x10**7 17F ions/s. The yield maintained this level until mid-January when the ORIC current was increased to 3-4 uA. This resulted in the yield increasing until near the end of the month where it attained a maximum of 5x10**7 17F ions/s. Since then, the yield has been gradually decreasing within the 10**7 17F ion/s level.

Thus, with this target configuration we have been able to sustain approximately an order of magnitude more 17F yield than with our previous best performing HfO2 target. Two effects can likely explain this improvement:

  • More efficient target configuration: more Al2O3 available for reaction
  • Better source operation: realization that target-ion source equilibrium conditions nominally take ~12 hours to achieve after a change is made to operation of the target.
It is likely that our low yields during the first month of operation can be explained by evaporation of the "in-beam" Al2O3 fiber disks creating unfavorably high vapor conditions in the ion source. These can be eliminated in our next configuration by completely shielding all the Al2O3 from the beam. In summary, this configuration to date provided approximately 900 hours of operation allowing the completion of several HRIBF experiments while, at times, providing an accelerated beam of over 10**6 17F ions/s on target.

RA3 - Experimental Equipment - Towards Digital Decay Spectroscopy of Proton Emitters

A new method of digital processing of DSSD preamplifier signals has been implemented at HRIBF for proton emission studies. It is based on the Digital Gamma Finder (DGF-4C) CAMAC modules produced by X-ray Instrumentation Associates (XIA), Mountain View, California ( http://www.xia.com). This change has been motivated by our desire to find the shortest-lived proton emitters. These nuclei are difficult to identify because the implantation of the heavy ion into the DSSD results in amplifier overload in the decay circuits. Now, DSSD preamplifier signals are processed and stored in the DGF module and are subsequently read via the VME data acquisition system. Each event energy is time stamped. Further data analysis and visualization is done within the standard ORNL acqusition system. Good energy resolution was achieved, about 24 keV for 5.5 MeV alpha particles from an external 241Am source. The lower energy threshold measured under real experimental conditions, for the decay of A=113 isobars, was as low as 150 keV. However, the recovery time went down to only about 4 us. For recoil implantation-proton decay correlation times below 4 us, the signals were rejected at the DGF level because they were recognized as pile-up. However, in the "reversed" operation mode of DGF modules, such pile-up events can be analyzed and stored as signal traces in amplitude vs 25 ns time bins (1k channels) spectra. This allows us to get the implant-decay correlation times down to about 400 ns and continue probing the traces up to about 7 us.

The contributions of UNIRIB collaboration and UT are greatly acknowledged. J. W. McConnell (ORNL), R. Grzywacz (UT), and M. Karny (UT) are the main persons implementing the new technique at HRIBF, in collaboration with M. Momayezi (XIA).

RA4 - Users Group News

The Users Group Executive Committee held a conference call on February 2, 2000. The first order of business was the resignation from the Committee of Lee Riedinger after he took office. According to the Users Group Charter, the remaining members are to select a replacement for the vacated seat. The committee selected Peter Parker (Yale) to fill out the remaining portion of Lee's term. We thank Lee for his past service and wish him well in his new duties (effective April 1) as ORNL's Deputy Director for Science and Technology.

One of the immediate duties of the new Committee is to choose a vice-chair to replace the present chair, I-Yang Lee, next year. This election was held and Kris Rykaczewski (ORNL) was selected.

RA5 - Experiments, Spokespersons, and Dates Run During the Past Quarter

November 1, 1999 - January 31, 2000

Experiment

Spokesperson/Institution

Dates

RIB-039 - High Voltage Injector Development

Mueller/ORNL

11/1-5/99
12/13-14/99

RIB-000 - Commissioning of the RMS

Gross/ORISE
Uribarri/ORNL

11/8-11/99
11/15/99
12/8/99
12/10/99
12/28/99

RIB-014 - Target-Ion-Source Development - Arsenic and Fluorine

Stracener/ORNL

11/12/99

RIB-040 - Beam Diagnostics Development

Shapira/ORNL

12/6/99
12/29/99

RIB-037 - Tandem Development

Meigs/ORNL

12/6-7/99
12/21/99
12/27/99
12/30/99
1/5/00

RIB-055 - Resonances in the 11B+1H System Below Ecm=2 MeV

Gomez del Campo/ORNL

12/9/99

RIB-031 - 18Ne Populated by Resonance Scattering of 18F on 1H Using Thick Targets

Uribarri/ORNL

12/15-20/99

RIB-017 - 17F + 208Pb Breakup Fusion at Near Barrier Energies

Liang/ORISE

12/22/99
1/7/00

RIB-019 - Proposal to Determine the 14O(a,p)17F Reaction Rate

Blackmon/ORNL

1/12-31/00

Scheduled Maintenance

12/30/99
1/3-4/00

Unscheduled Maintenance

11/16-24/99
11/29-12/3/99
1/6-7/00
1/11-12/00
1/13/00


For this quarter's schedule go to http://www.phy.ornl.gov/hribf/users/01-03-2000.html.





Additional copies of the newsletter and more information about HRIBF can be found on the World Wide Web at www.phy.ornl.gov. You may contact us at the addresses below.

Witek Nazarewicz Carl J. Gross
Deputy Director for Science Scientific Liaison
Mail Stop 6368 Mail Stop 6371
witek@mail.phy.ornl.gov cgross@mail.phy.ornl.gov
+1-865-574-4580 +1-865-576-7698

Holifield Radioactive Ion Beam Facility
Oak Ridge National Laboratory
Oak Ridge, Tennessee 37831 USA
Telephone: +1-865-574-4113
Facsimile: +1-865-574-1268