measurement of 58 co gamow-teller strength via (t, 3 he) arthur l. cole national superconducting...
Post on 18-Dec-2015
219 Views
Preview:
TRANSCRIPT
Measurement of 58Co Gamow-Teller Strength via (t,3He)
Arthur L. Cole National Superconducting Cyclotron Laboratory,
Michigan State University
ref: ESA
53Mn 59Ni56Fe
56Fe 53Cr55Mn
*
* * DominantStable
100101102103104105
Time till core collapse (s)
0.42
0.44
0.46
0.48
0.50
1 H53 Cr
57 Fe56 Fe
56 Fe55 Fe
54 Fe55 Co WW
LMP
10 010 110 210 310 410 510 60.42
0.44
0.46
0.48
0.50
55 Fe57 Co
57 Fe61 Ni
57 Fe53 Cr 57 Fe
53 Cr
WWLMP
25 M
15 M
Most important electron-capturing nuclei
Time till core collapse(sec)
53Mn59Ni56Fe
56Fe 53Cr55Mn
*
* * DominantStable
10 010 110 210 310 410 5
Time till core collapse (s)
0.42
0.44
0.46
0.48
0.50
1 H53 Cr
57 Fe56 Fe
56 Fe55 Fe
54 Fe55 Co WW
LMP
10 010 110 210 310 410 510 60.42
0.44
0.46
0.48
0.50
55 Fe57 Co
57 Fe61 Ni
57 Fe53 Cr 57 Fe
53 Cr
WWLMP
25 M
15 M
Most important electron-capturing nuclei
Time till core collapse(sec)
Motivation: Electron Capture
WW: Woosley, Weaver (FFN) w/ Independent Particle ModelLMP: Langanke, Martinez-Pinedo; Heger, Langanke w/ Shell Model
Independent ParticleModel (IPM)
Shell Model (SM)
protons neutrons
f7/2
f5/2
protons neutrons
Need Experiment totest and validatemodel calculations
Example: 56Ni28+56Co27+
Heger et al. (2001)Core Collapse Supernovae,
Pre-collapse Stage:EC influences pressure,
entropy, electron fraction (Ye)
Gamow-Teller Strength, B(GT)
Study Electron Capture: e- + 58Ni 58Co + via Charge-Exchange : t + 58Ni 58Co + 3He
eν
Fujiwara et al. (1996)
(3He,t))()0(
2GTBJKNq
d
dD στ
σ==
Ω
Linearity
Gamow-Teller: ∆L = 0, ∆S = 1, ∆T = 1
Charge-Exchange Reactions
n + 58Ni 58Co + p 58Ni(n, p) 58Co•resolution ≥ 1 MeV, Good linearity (p,n), well studied
d + 58Ni 58Co + 2He 58Ni(d, 2He) 58Co •resolution ≥ 100-160 keV, Complex reaction mechanism
t + 58Ni 58Co + 3He 58Ni(t, 3He) 58Co•resolution ≥ 160-200 keV, Good linearity
Study EC: e- + 58Ni 58Co + 58Ni(e, )58Co via (n,p), (d,2He), (t,3He)
eν eν
FWHM ~ 250 keV
Linearity
Resolution)()0(2GTBJKNq
d
dD στ
σ==
Ω
Ebeam > 100 MeV/nucleon
The Experimentt + 58Ni 58Co + 3He 58Ni(t, 3He) 58Co
TargetTarget
beam t ~112 MeV/nucleon
3He
t
t
n pn
n pp
58Ni: 7.61 mg/cm2 CH2: 6.72 mg/cm2
D2
D1
Detectors
S800 Spectrometer
Gamow-Teller
Spin-flip, S=1
Multipole Decomposition Analysis
MDA w/ Distorted Wave Born Approximation
Ex(58Co) 1.75-2 MeV
€
B(GT)∝dσ (q = 0)
dΩ
FWHM ~ 250 keV
Gamow-Teller Strength, B(GT)
•58Ni(t,3He)58Co Data more like 58Ni(d,2He)58Co
•Need Experiment to Test and Validate Models
•58Ni(t,3He)58Co at NSCL•58Ni(n,p)58Co at TRIUMF•58Ni(d,2He)58Co at KVI Large-scale SM (KB3G) 1-MeV rebinned
Collaboration
A.L. Cole, R.G.T. Zegers, S.M. Austin, D. Bazin, G.W. Hitt, B.M. Sherrill, M. Steiner, National Superconducting Cyclotron Laboratory, H. Akimune, Konan University, A.M. Van Den Berg, G.P.A. Berg, M.N. Harakeh,Kernfysisch Versneller Instituut, Y. Fujita, H. Ueno,Osaka University, M. E. Howard, The Ohio State University, Daito, M. Fujiwara, K. Hara,Research Center for Nuclear Physics, Osaka University, T. Kawabata, RIKEN, T. Nakamura, Toyko Institute of Technology, J. Jänecke, University of Michigan, J. Brown, Wabash College
top related