High-resolution studies of beta-delayed proton emission in light nuclei

Thesis/Dissertation · Sat Dec 01 04:00:00 EST 1973

DOI:https://doi.org/10.2172/4322678· OSTI ID:4322678

Sextro, Richard George ^[1]

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1. Univ. of California, Berkeley, CA (United States)

Thesis. Identified protons were observed following beta decay of the precursor nuclei ²¹Mg, ²⁵Si, ³⁷Ca, ⁴⁰Sc, ⁴¹Ti, and ²³Al. These measurements spanned a proton energy range from 600 keV to 8.5 MeV, and included all significant particle decays of these nuclei. A helium-jet transport system was developed and used with various DELTA E - E counter telescopes to obtain high-resolution, lowbackground spectra. These data perrmitted accurate location of proton unbound levels in the beta-decay daughters, and absolute branching ratios and ft values for these allowed decays were determined. The half-lives of these nuclei were measured, and all except that for ⁴¹Ti are consistent with the previous values. For ⁴¹Ti, the half-life is 80 plus or minus 2 msec, which differs from the old value of 88 plus or minus 1 msec. This latter value is thought to have been affected by the presence of ³⁷Ca activity produced in a competing reaction. The ft values for ²¹Mg and ²⁵Si are compared to the negatron decay rates in their respective mirrors. For mass 21, s 1.17 plus or minus 0.04. A comparison of predicted and observed beta-decay rates for the superalloyed decay to the T = 3/2 state in /sup 41/Sc indicates that this level has an isospin impurity of ~8%. The observed beta-decay rates in ²¹Mg and ³⁷Ca are also contrasted with theoretical predictions for decay rates to their respective daughters. The calculated values agree well for ²¹Mg, while for ³⁷Ca the calculations appear to be limited by the basis space used. Delayed protons from ²³Al, the first member of the A =4 n + 3 series of T_z = 3/2 nuclei, were observed, and the half-life of ²³Al was measured to be 470 plus or minus 30 msec. In addition, delayed protons from ⁴⁰Sc were studied in order to ascertain their contribution to the proton spectra obtained from ³ He bombardment of ⁴⁰Ca.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: US Atomic Energy Commission (AEC)
• DOE Contract Number: W-7405-ENG-48
• NSA Number: NSA-29-030734
• OSTI ID: 4322678
• Report Number(s): LBL--2360
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALUMINIUM 23-- BETA-PLUS DECAY-- BRANCHING RATIO-- CALCIUM 37-- DELAYED PROTONS-- FT VALUE-- HALF-LIFE-- MAGNESIUM 21-- PROTON SPECTRA-- SCANDIUM 40-- SILICON 25-- TITANIUM 41
ALUMINIUM 23-- COMPOUND-NUCLEUS REACTIONS-- EXCITATION FUNCTIONS-- MAGNESIUM 24-- MEV RANGE 10-100-- NEUTRONS-- PROTON REACTIONS
ALUMINIUM 25-- CALCIUM 40-- ENERGY LEVELS-- MAGNESIUM 23-- POTASSIUM 37-- SCANDIUM 41-- SODIUM 21
N68421* --Physics (Nuclear
Experimental)--Nuclear Properties & Reactions
20 <= A <= 38--Radioactive Decay
N68431 --Physics (Nuclear
Experimental)--Nuclear Properties & Reactions
20 <= A <= 38--Energy Levels & Transitions
N68451 --Physics (Nuclear
Experimental)--Nuclear Properties & Reactions
20 <= A <= 38--Nuclear Reactions & Scattering
N68521 --Physics (Nuclear
Experimental)--Nuclear Properties & Reactions
39 <= A <= 58--Radioactive Decay
N68531 --Physics (Nuclear
Experimental)--Nuclear Properties & Reactions
39 <= A <= 58--Energy Levels & Transitions