Ground state Gamow-Teller strength in sup 64 Ni(n,p) sup 64 Co

Conference · Tue Jan 01 00:00:00 EST 1991

OSTI ID:5753361

Ling, A; Haight, R C; King, N S.P.; Lisowski, P W; Sorenson, D S; Ullmann, J L ^[1]; Aslanoglou, X; Finlay, R W; Park, B K; Rapaport, J ^[2]; Brady, F P; Romero, J L ^[3]; Howell, C R; Tornow, W ^[4]

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1. Los Alamos National Lab., NM (USA)
2. Ohio Univ., Athens, OH (USA)
3. California Univ., Davis, CA (USA)
4. Duke Univ., Durham, NC (USA)

An important process occurring in presupernova stars is e{sup {minus}} capture on free protons and nuclei. As e{sup {minus}} capture and the charge exchange reaction (n,p) between same initial and final states are both T{sub 0} {yields} T{sub 0} + 1 transitions involving the same nuclear matrix element, the (n,p) reaction can be used to provide the input required to calculate e{sup {minus}} capture rates. Specifically, the e{sup {minus}} capture rate {lambda}{sup if} for a nucleus going from an initial state i to a final state f is proportional to the Gamow-Teller strength B{sup if}. Once B{sup if} for a particular transition is known, the corresponding e{sup {minus}} capture rate {lambda}{sup if} for that transition can be calculated. The unit cross section {cflx {sigma}}{sub GT}(E,A) relates B{sup if} to the zero degree differential cross section extrapolated to q = 0 for (n,p) or (p,n) reactions: {sigma}(q = 0) = {cflx {sigma}}(E,A)B{sup if}. As {cflx {sigma}}(E,A) has been seen to have a smooth A dependence, measurements of zero degree (n,p) cross sections for (fp) shell nuclei can be used to obtain B{sup if}, and thus {lambda}{sup if}, once a value for {cflx {sigma}}(E,A) in this mass region is known. The data presented here allow a value for {cflx {sigma}}{sub GT} in the (fp) shell to be calculated from the Gamow-Teller strength for the {beta}{sup {minus}} decay {sup 64}Co {yields} {sup 64}Ni + e{sup {minus}} + {bar {nu}}{sub e}. Since {sup 64}Co {beta}{sup {minus}} decay and the reaction {sup 64}Ni(n,p) {sup 64}Co have opposite initial and final states, detailed balance can be used to relate the Gamow-Teller strengths for the two processes: B{sup np} = 0.6228{sub {minus}.0369}{sup +.0328}. It is this value of B{sup np} together with the differential cross section measurements presented here for the reaction {sup 64}Ni(n,p) {sup 64}Co that allow {cflx {sigma}} to be calculated and thus a calibration point in the (fp) shell is established.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 5753361
• Report Number(s): LA-UR-91-1320; CONF-9103165-2; ON: DE91011437
• Resource Relation: Conference: International conference on spin and isospin in nuclear interactions, Telluride, CO (USA), 11-15 Mar 1991
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
NICKEL 64 TARGET
NEUTRON REACTIONS
ANGULAR DISTRIBUTION
BRANCHING RATIO
CROSS SECTIONS
EXPERIMENTAL DATA
GAMOW-TELLER RULES
GROUND STATES
BARYON REACTIONS
DATA
DISTRIBUTION
ENERGY LEVELS
HADRON REACTIONS
INFORMATION
NUCLEAR REACTIONS
NUCLEON REACTIONS
NUMERICAL DATA
TARGETS
651620* - Nuclear Properties & Reactions
A=59-89
Experimental