Lifetimes of excited states of fp-shell nuclei

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:5055269

Pate, S F

Lifetimes of excited states of {sup 51}Sc, {sup 51}T, and {sup 55}Cr have been measured with the Doppler-shift attenuation method. The reactions used to produce these nuclei were {sup 48}Ca({alpha},p{gamma}){sup 51}Sc(E{sub {alpha}} = 15 MeV), {sup 50}Ti(d,p{gamma}){sup 51}Ti (E{sub d} = 6 MeV), and {sup 54}Cr(d,p{gamma}){sup 55}Cr (E{sub d} = 4 MeV). Protons were detected using a position sensitive silicon surface-barrier detector (with discrete position sensitivity) with a solid angle of approximately 1 sr. {gamma} rays were detected in coincidence with the protons using high-purity coaxial Ge crystals. Despite the very small ({alpha},p) cross section (compared to ({alpha},n) and ({alpha},2n)), {gamma} rays from several states of {sup 51}Sc were observed; lifetime information was obtained for three states. Most of the states observed with the (d,p) reactions were low spin states, and most of the lifetimes were in the 10-500 fs range, implying strong M1 contributions. The measurements in {sup 51}Ti are in good agreement with a very recent measurement by another group; in addition we observe the decay of several more states. A large number of new {sup 55}Cr excited state lifetimes were measured. Shell model calculations were performed for negative parity levels in these nuclei using an effective interaction due to Koops and Glaudemans and van Hees and Glaudemans. The energy spectra, (d,p) spectroscopic factors, and lifetimes from these calculations are in very good agreement with the data, although because of computational restrictions imposed on the {sup 55}Cr calculation the agreement there is not as close as in {sup 51}Sc and {sup 51}Ti.

• Research Organization: Pennsylvania Univ., Philadelphia, PA (USA)
• OSTI ID: 5055269
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400101* -- Activation
Nuclear Reaction
Radiometric & Radiochemical Procedures
640302 -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHROMIUM 55
CHROMIUM ISOTOPES
DATA
DOPPLER EFFECT
ENERGY LEVELS
EVEN-ODD NUCLEI
EXCITED STATES
EXPERIMENTAL DATA
INFORMATION
INTERMEDIATE MASS NUCLEI
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LIFETIME
MEASURING INSTRUMENTS
MEASURING METHODS
MINUTES LIVING RADIOISOTOPES
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
RADIOISOTOPES
SCANDIUM 51
SCANDIUM ISOTOPES
TITANIUM 51
TITANIUM ISOTOPES