HRIBF NEWS

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   Edition 1, No. 2               November 11, 1993            Price: FREE
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1. Workshop on Focal Plane Detectors.

A workshop on the design and construction of detectors for the focal plane of the HRIBF Recoil Mass Separator (RMS) will be held at the Joint Institute for Heavy Ion Research in Oak Ridge Thursday and Friday December 2 and 3. This meeting is slated to start at 1 p.m. Thursday and to end at about 5 p.m. Friday. Friday's lunch will be provided.

The purpose of this informal workshop is to determine what detectors are needed for the RMS and who is interested in participating in their design and construction. The compatibility of various detection systems and the possibility of making more than one measurement at the same time also will be considered. For example, a tape system could be operated downstream of the focal-plane detector during "in-beam gamma-ray experiments" in which a charged-particle array at the target position is used for Z identification. What other experiments could be performed simultaneously?

People interested in participating in this workshop should contact Carl Gross (email: cgross@orph01) prior to November 20. Carl will acknowledge receipt of your email messages. Persons planning to stay overnight in Oak Ridge are responsible for making their own reservations. It is crucial that participants who are not U.S. citizens contact Carl as soon as possible, so that the proper authorization can be obtained for their attendance.

Please let Carl know in advance if you wish to propose a specific detection system, and he will schedule a short presentation. Also note that Cary Davids (Argonne National Laboratory) will present the Physics Division Seminar at 3 p.m. on Thursday, December 2. He will speak on results from the Argonne FMA.

2. Delivery and Testing of the High Temperature CERN-ISOLDE-Type Ion Source.

The CERN-ISOLDE positive ion source is in the class of electron-beam plasma ion sources in which the mechanism of ionization is by electron impact. The high-temperature version of this source has been selected as one of the principal sources for RIB generation at HRIBF because of its low emittance, relatively high ionization efficiency, and species versatility. Of equal importance, the source has been engineered for remote installation, removal and servicing as required for safe handling in a high-radiation level ISOL facility such as HRIBF. An ORNL version of this source has been designed, fabricated, assembled, and installed on the HRIBF Ion Source Test Facility, and initial vacuum integrity tests were completed in time to meet an August 31 Martin-Marietta milestone. During the next several weeks, the basic operational parameters, ionization efficiencies, and the emittances of the source will be determined. Planned activities include thermal-characterization studies such as the dependence of the target, cathode and anode temperatures on input power and their inter-dependencies, measurement of the ionization efficiencies for the noble gases (He, Ne, Ar, Kr, and Xe) and measurement of the beam emitance prior to momentum analysis.

3. Delivery and Testing of the High Voltage Platforms.

The 300-keV high-voltage platform system for the RIB injection was delivered to ORNL from the manufacturer, National Electrostatics Corporation, October 4. The platform system was installed in room C111 and successfully tested. The potential ripple of the injector system will be about 10 volts peak-to-peak at an operating potential of 300 KV. Installation of the RIB injector on the high-voltage platform will soon start.

4. Working Groups Associated with HRIBF Detection Systems.

In order to solicit input from potential users of HRIBF for the various new detection systems that are planned we are in the process of organizing a series of working groups associated with each detector. People interested in participating in one of these groups should contact the appropriate ORNL coordinators listed below who is associated with the detector of interest:

    RMS                         Ron Auble (auble@orph01)
    RMS Focal-plane Detectors   Carl Gross (cgross@orph01)
    Germanium Array Upgrade     Noah Johnson (johnson@orph01)
    Charged-particle Microball  Cyrus Baktash (baktash@orph01)
    Astrophysics                Michael Smith (msmith@orph01)
    Neutron Detectors           Cyrus Baktash (baktash@orph01)
    Data-Analysis Software      Bill Milner (milner@orph01).

5. Marcel Arnould to Lecture on Nuclear Astrophysics at ORNL.

Marcel Arnould, Professor of Astrophysics at the Universite Libre de Bruxelles, will visit ORNL on Monday and Tuesday, November 22 and 23. He will lecture on "From the Nuclear Physics Laboratory to the Cosmos" at 11:00 a.m. on Monday November 22. An abstract of his talk is given below:

"The last decades have put to the forefront the especially fruitful interplay between nuclear physics and astronomy. That successful inter-disciplinary field is commonly referred to as 'Nuclear Astrophysics'.

"Nuclear astrophysics deals with two classes of problems: (1) the energy production in various objects ranging from 'quiet' stars to spectacular events of explosive nature; and (2) the production of the nuclides observed in the universe and in particular in our solar system. The nuclear physics studies that are required in order to tackle those problems are of both experimental and theoretical nature, and concern a large variety of questions. One important category of problems relates to the determination of nuclear reaction cross sections at energies of astrophysical interest. Another one has to do with the knowledge of other nuclear quantities, like masses or beta-decay half-lives of exotic nuclei.

"After the presentation of some generalities and a brief synopsis of the theoretical and experimental procedures that are commonly used in nuclear astrophysics, the talk will review some reactions important to astrophysics which have been studied recently, or which would be worth investigating in some detail. The nuclear physics problems that are raised by the modeling of the synthesis of the nuclides heavier than iron will also be considered."

6. How to Unscribe to this Newsletter.

If you wish not to receive future copies of the HRIBF News please inform Jerry Garrett (email: garrett@orph01).

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**                                                                           **
**        J. D. Garrett                   Phone:  (615) 576 5489             **
**                                        Fax:    (615) 574 1268             **
**                                        Email:  garrett@orph01             **
**                                                                           **
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