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

Gamow-Teller?

FWHM ~ 250 keV

58Ni(t, 3He) 58Co at 112 Mev/nucleon

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