Hope College Department of Physics and Engineering Research Experiences for Undergraduates Summer 2001 Project Summary

Project Title: Construction of neutron detectors and analysis of Neutron transfer reactions in an experiment performed at Notre Dame
Student Name: Joseph Bychowski
Student’s home institution: Hope College
Research Advisor(s): Dr. Paul DeYoung
Source of Support (NSF-REU, or other): NSF-REU

This summer I worked on two very different projects. The first project is the construction of a neutron detection wall. I spent most of the summer working on this project. My second project is the analysis of the ²⁰⁹Bi(⁶He,a ) experiment Performed at Notre Dame this summer.

In nuclear physics experiments it is important to know the properties of the neutrons produced in the experiment. In many cases knowing the angular distribution and energy distribution of the emitted neutrons is the key to understanding the reaction dynamics. Small detectors, two to five inches in diameter, normally would be placed at strategic angular positions around the target chamber in the attempt to understand the neutron properties. In radioactive beam experiments using small detectors is a problem because of the inherently low beam intensity. Large detectors, like the one that I am building, will overcome this problem.

The neutron detection wall will consist of eight plastic scintillators stacked on top of each other. The scintillators are five feet by two inches by six inches. Each of the scintillators had to be cleaned and rewrapped. Repairs were made to the electrostatic shield. Then the scintillators were reattached to light guides and photo-multiplier tubes.

As construction of each detector slat was completed the detector characteristics were measured. We measured the position resolution and the efficiency of the detectors. In order to fix the position of the events in the detector slat a small trigger detector was used. Measurements were taken from five different positions along the detector slat. Because different types of radiation have different detection properties these measurements were taken using two different types of radiation: cosmic rays, which have a high energy, and ⁶⁰Co gamma rays, which have a lower energy. The position of an event can be found by two different methods: signal time difference, and by signal attenuation. The signal time difference method is based upon the fact that light travels at a finite speed. The light takes longer to get to one end or another depending on where the event took place and by measuring this difference we can measure position. The signal attenuation method is based upon the fact that as the light travels though the detector slat it is attenuated. So depending on where the event took place, it will register as having different amplitude in each end of the detector slat. By measuring the amplitude at each end and normalizing to the total, we can measure the position. We performed tests using both methods. The detector efficiency was measured because it is possible that as the light from an event travels to the photomultiplier tubes the signal attenuates to the point that the electronics will not register it. This has the greatest probability of happening when the event occurs at one of the ends of the detector slat. We defined an efficiency ratio as the number of full events, meaning that the event registered in the trigger and in both ends of the detector slat, divided by the number of events in the trigger. This number by itself is not very useful because the radiation that registered in the trigger detector does not necessarily go though the detector slat, but when the efficiencies taken at each of the five positions on the detector are compared we can learn about the position dependence of the efficiency. The preliminary results for the detector characteristics are summarized in the following table.
 

The detectors will be installed at Notre Dame University and will be used by research groups from several institutions, including Notre Dame, Hope College, Indiana State University South Bend, and University of Michigan.

My second project is the analysis of neutron transfer reactions in an experiment performed at Notre Dame. The experiment was a ⁶He secondary beam on a ²⁰⁹Bi target. Fortran programs were created to reformat the data from the format that is used at Notre Dame to a format that our data analysis program, IDL, could read easily and efficiently. I was also able to recreate many of the spectra that were seen at Notre Dame. Work on this experiment is in the earliest stages but will be continued this fall.

Slide show of Joseph Bychowski's work
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Publications and Presentations:
“Doppler Shift as a Tool for Studies of Resonant (p,n) Reactions with RIBs: Spectroscopy of ⁷He.” P. Boutachkov, G.V. Rogachev, V.Z. Goldberg, A. Aprahamian, F.D. Becchetti, J.P. Bychowski*, Y. Chen, G.Chubarian, P.A. DeYoung, J.J. Kolata, L.O. Lamm, G.F. Peaslee, M. Quinnm, B.B. Skorodumov, A. Wöhr. AIP Conf. Proc. 819, 221 (2006).
“A Large Segmented Neutron Detector for Reaction Studies with Radioactive Beams Near the Coulomb Barrier.” J.J. Kolata, H. Amro, M. Cloughesy, P.A. DeYoung, J.P. Bychowski*, J. Reith*, and G. Peaslee. Nucl. Instr. And Meth. A557, 594 (2006).
“Doppler Shift as a Tool for Studies of isobaric Analog States of neutron-Rich Nuclei: Application to ⁷He.” P. Boutachkov, G.V. Rogachev, V.Z. Goldberg, A. Aprahamian, F.D. Becchetti, J.P. Bychowski*, Y. Chen, G. Chubarian, P.A. DeYoung, J.J. Kolata, L.O. Lamm, G.F. Peaslee, M. Quinn, B.B. Skorodumov, and A. Wöhr. Phys. Rev. Lett. 95, 132502 (2005).
“Isobaric Analog States of Neutron-Rich Nuclei. Doppler Shift as a Measurement Tool for Resonance Excitation Functions.” P. Boutachkov, G.V. Rogachev, V.Z. Goldberg, A. Aprahamian, F.D. Becchetti, J.P. Bychowski*, Y.Chen, G. Chubarian, P.A. DeYoung, J.J. Kolata, L.O. Lamm, G.F. Peaslee, M. Quinn, B.B. Skorodumov, and A. Wöhr. Eur. Phys. J. A25, 259 (2005).
“The (⁸Li, α) reaction at Low Energy: Direct ⁴H Cluster Transfer?” F.D. Becchetti, R.S. Raymond, D.A. Roberts, J. Lucido, P.A. DeYoung, B. Hilldore*, J. Bychowski*, A.J. Huisman*, P.J. VanWylen*, J.J. Kolata, G. Rogachev, and J.D. Hinnefeld. Phys. Rev. C 71, 054610 (2005).
“Construction of a Modular Large-Area Neutron Detector.” T. Baumann, J. Boike*, J. Brown, M. Bullinger, J.P. Bychoswki*, S. Clark*, K. Daum*, P.A. DeYoung, J.V. Evans*, J. Finck, N. Frank, A. Grant, J. Hinnefeld, G.W. Hitt, R.H. Howes, B. Isselhartdt*, K.W. Kemper, J. Longacre*, Y. Lu, B. Luther, S.T. Marley*, D. Mccollum*, E. McDonald*, U. Onwuemene*, P.V. Pancella, G.F. Peaslee, W.A. Peters, M. Rajabali*, J. Robertson*, W.F. Rogers, S.L. Tabor, M. Thoennessen, E. Tryggestad, R.E. Turner*, P.J. VanWylen*, and N. Walker*. Nucl. Instr. And Meth. A543, 517 (2005).
“Doppler Shift as Spectroscopy Tool in Experiments With Unstable Beams and its Application for ⁷He.” P. Boutachkov, G.V. Rogachev, A. Aprahamian, J.J. Kolata, L.O. Lamm, M. Quinn, B.B. Skorodumov, A. Wohr, V.Z. Goldberg, G. Chubarian, J.P. B;ychowski*, P.A. DeYoung, G.F. Peaslee, F.D. Becchetti, and Y. Chen. Paper BC.002. Division of Nuclear Physics Fall Meeting. Chicago IL, October 2004.
“²⁰⁹Bi(⁶He,α) Reaction Mechanisms Studied Near the Coulomb Barrier Using n-a Coincidence Measurements.” J.P. Bychowski*, P.A. DeYoung, BB. Hilldore*, J.D. Hinnefeld, A. Vida*, F.D. Becchetti, J. Lupton, T.W. O’Donnell, J.J. Kolata, G. Rogachev, and M. Hencheck. Phys. Lett. 596B, 26 (2004).
“Analog states of ⁷He Observed via the ⁶He(p,n) Reaction.” G.V. Rogachev, J. Bychowski*, P. Boutachkov, A. Aprahamian, F.D. Becchetti, Y. Chen, G. Chubarian, P.A. DeYoung, V.Z. Goldberg, J.J. Kolata, G.F. Peaslee, M. Quinn, B.B. Skorodumov, and A. Wöhr. Rev. Lett. 92, 232502 (2004).
“Study of the (⁸Li,α) Reaction at Low Energy: Direct ⁴H Transfer?” F.D. Becchetti, D.A. Roberts, J. Lucido, P.A. DeYoung, B. Hilldore*, J. Bychowski*, J.J. Kolata, and G. Rocharchev. The Sixth International Conference on Radioactive Nuclear Beams, Argonne, Il, September 2003.
“The MoNA Project.” P.J. VanWylen*, J.P. Bychowski*, P.A. DeYoung, G.F. Peaslee, and the MoNA Consortium. Paper 5P1.071. Division of Nuclear Physics Fall Meeting. East Lansing, MI, October 2002.
“Understanding the ²⁰⁹Bi(⁶He,⁴He) Reaction Mechanisms Near the Coulomb Barrier.” J.P. Bychowski*, P.A. DeYoung, B.B. Hilldore*, J.D. Hinnefeld, A. Vida, F.D. Becchetti, J. Lupton, T.W. O’Donnel, J.J. Kolata, G. Rogachev, and M. Hencheck. Paper 5P1.072. Division of Nuclear Physics Fall Meeting. East Lansing, MI, October 2002.
“Construction of a Neutron Detection Wall.” J. Bychowchski*, and P.A. DeYoung. PEW Midstates Consortium Undergraduate Research Symposium, University of Chicago, November 2001.