Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1962 A Study of the Reactions, Beryllium-9(helium-3,neutron)carbon-11, Lithium-7(helium-3,neutron)boron-9 and Carbon-13(helium-3,neutron)oxygen-15 by Time- Of-Flight Techniques. Jerome Lewis Duggan Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Recommended Citation Duggan, Jerome Lewis, "A Study of the Reactions, Beryllium-9(helium-3,neutron)carbon-11, Lithium-7(helium-3,neutron)boron-9 and Carbon-13(helium-3,neutron)oxygen-15 by Time-Of-Flight Techniques." (1962). LSU Historical Dissertations and Theses. 718. https://digitalcommons.lsu.edu/gradschool_disstheses/718 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. This dissertation has been 62—3644 microfilmed exactly as received DUGGAN, Jerome Lewis, 1933- A STUDY OF THE REACTIONS, Be9(He3,n)Cn , Li7(He3,n)B9 AND C13(He3,n)Ol5 , BY TIME-OF- FUGHT TECHNIQUES. Louisiana State University, Ph.D., 1962 Physics, nuclear University Microfilms, Inc., Ann Arbor, Michigan A STUDY OF THE REACTIONS, Be9(He3 ,n)C1;L, L i7(He3,n)B AND C13(He3 ,n )0 15, BY TIME-OF-FLIGHT TECHNIQUES A D issertation Submitted to the Graduate Faculty of the Louisiana State University and A gricultural and Mechanical College in partial fulfillm ent of the requirements for the degree of Doctor of Philosophy i n The Department of Physics by Jerome Lewis Duggan B. A., North Texas State College, 1955 M. A., North Texas State College, 1956 January, 1962 ACKNOWLEDGMENT The author wishes to express his appreciation and gratitude to his research advisors, Dr. P. D. M iller and Dr. W. M. Good of the Oak Ridge National Laboratory and Dr. V. E. Parker of Louisiana State University, for their assistance and encouragement during the course of this work. In addition he wishes to thank Dr. R. F. Gabbard of the University of Kentucky, Dr. J. H. Neiler, Dr. G. R. Satchler, Mr. R. P. Cumby and Mr. M. C. Taylor of the Oak Ridge National Laboratory for their assistance in this project. Also, appreciation is due Mrs. B. A. Denning for typing the manuscript of this thesis. Finally, he would like to recognize the financial support of the Graduate Fellowship Program of the Oak Ridge Institute of Nuclear Studies and the Physics Division of the Oak Ridge National Laboratory. TABLE OF CONTENTS PAGE ACKNOWLEDGMENT................................................................................................................. i i LIST OF TABLES................................................................................................................. v LIST OF FIGURES ............................................................................................................ v i ABSTRACT................................................................................................................................ x l CHAPTERS I. INTRODUCTION......................................................................................................... 1 The Importance of He R eactions ................................................. 1 Reaction M echanisms ............................................................................... 3 The Levels in $ } , an d C ^ ...................................................... 9 I I . EXPERIMENTAL APPARATUS AND PROCEDURE.............................................. 15 Spectrometer Resolving Power ........................................................... 15 Sources of Energy Spread ............................. 18 Elapsed Time M easurement ..................................................................... 21 Refinements for (He ,n) R eactions ............................................ 23 Electronics .................................................................................................. 33 I I I . PRESENTATION OF DATA.................................................................................... 44 Plastic Scintillator Efficiency ................................................. 44 Pulse S pectra ............................................................................................. 48 The Be^(He^Jn)C11 R eaction ................................................................ 51 The C13(He3,n)015 Reaction ................................................................ 53 The Li^(He3,n)B^ R eactio n ........................ 65 CHAPTERS - ■ PAGE Measured Q V alu es ................................................................................... 72 Discussion of Errors ............................................................................... j6 IV . CALCULATIONS AND RESULTS.......................................................................... 80 Plane Wave C alculations ............................. 80 Distorted Wave C alcu latio n s .............................................................. 90 Discussion of Theoretical Calculations and Results . 95 BIBLIOGRAPHY..................................................................................................................... I l 6 APPENDIX..................................................................................................................................... 121 V LIST OF TABLES TABLE PAGE I. Measured Q, V alues ............................................................................................... 77 II. Spin and Parity Assignments ...................................................................... 96 III. Optical Model Param eters ........................................................................... 97 LIST OF FIGURES FIGURE PAGE 1. Reciprocal Velocities for Neutron Groups from Be'^(He3 ,n )C '^ ‘ ...................................................................................................20 2. Block Diagram of Post Acceleration Pulsing S ystem ......................... 25 3. Average Target Current vs Reciprocal Pulser V oltage............................. 26 M easured 7 -Ray Duration vs Pulser V oltage ..............................................27 5 . Electronics Used to Study Time Resolution P a r a m e t e r s ...................................................................................................................... 3° 6 . Time Converter ...................................................................................... 3k 7 . Block Diagram for Time-of-Flight Spectrum............................................. 35 8 . Time-of-Flight Spectrum for Neutrons from C1 3 (He3 ,n ) 0 15 at 0 ^ = 0°, E ^ ~ 2 Mev and Flight Path 3 m...........................* ................................................................37 9. Time Spectrum for In7(He 3 ,n )B ? a t ER 3 = 2 .3 5 Mev, 0=0° and Flight P a th 6 m. j f ............................................................................................................ 38 10. Time Spectrum for Be^(He3,n)C'*"*' a t Eg e 3 = 2 .5 Mev, 0 = 0° and Flight Path 6 m..................................................................................39 11. Block Diagram for Pulse Spectrum ................................................................l)-0 12. Pulse Height Spectrum for 9*83 Mev Neutrons from Be^(He3,n )C '1''*' ^1 13. Block Diagram for Pulse Spectrum with Memory S p litte r ........................................................................................................k2 v i i FIGURE PAGE 14. Calculated Efficiency of ^ x 3 in. Plastic Scintillator ........................................................................................................ 47 1 5 . Theoretical Pulse Spectra of 10-Mev Neutrons for 4 x 3 in. Plastic S cin tillato r .................................................. 5 ° 1 6 . Absolute Efficiency of 3 x 4-in. Plastic Scintillator with Bias Level at 1.1 Mev ........................................... 52 1 7 . Angular Distribution for Ground State Neutrons from Be^(He'^,n)C 11 a t ERe3 = 2 .1 Mev .................................................. 5^ 18s. Angular D istribution of 1st Excited State Neutrons from Be (He ,n)C at EHe3 = 2 .1 Mev ........................................................................................................ 55 1 9 . Angular Distribution for 2nd Excited State Neutrons from Be^(He^,n)C‘^ ‘ at EHe3 = 2 .1 Mev ........................................................................................ 56 20. Angular Distribution of 3rd Excited state Neutrons from Be^He^nJC 11 a t EHe3 = 2 .1 Mev ........................................................................................................ 57 21. Angular Distribution of 4th Excited State Neutrons from Be^(He^,n)C^ at ERe3 = 2 .1 Mev ......................................................................................................... ~ 58 22. Excitation Function for Be^(He^,n)C'^‘, Ground State Neutrons ............................................................................... 59 2 3 . Excitation Function for Be^(He^,n)C^, 1st Excited State ......................................................................................... 60 FIGURE 9 3 11 2b. Excitation Function for Be (He ,n)C , 2nd Excited State .................................. ............................ 2 5 . Excitation Function of the 3rd Excited S tate