55 Co
1
The NSCL is funded in part by the National Science Foundation and Michigan State University. 55 Co S800 PID - 56 Ni(d, 3 He) 55 Co Target (p / d) 56 Ni Beam Φ To S800 Spectrograph 55 Ni / 55 Co (measure P,E,Φ) MCP's θ d / 3 He HiRA Results Experimental Setup Inverse kinematics at 37MeV/A, 80MeV/A R. Shane 1* , T. K. Ghosh 2 , A. Sanetullaev 1 and M. B. Tsang 1 For the HiRA Collaboration 1 National Superconducting Cyclotron Laboratory, Michigan State Univ., East Lansing, MI 48824, USA 2 Variable Energy Cyclotron Centre, 1/AF, Bidhannagar, Kolkata 700064, India * E-mail: [email protected] The global OM potentials obtained from systematic analysis of (p,d) and (d,p) transfer reactions at low-energy do not seem to work at higher energy. Work on extraction of the neutron and proton SF from the higher-energy data, as well as a consistent framework for comparison to the low-energy results, is in progress. HiRA + S800 @NSCL High Resolution Array (HiRA) 56 Ni: An alluring nucleus 56 Ni is outside the valley of stability and is doubly magic according to the Independent Particle Model (IPM) In the shell model, the magic number 28 is the first shell that requires the introduction of a strong spin-orbit interaction 56 Fe is the most abundant heavy element in the universe, yet 56 Ni is the first doubly-magic nucleus that is not stable 56 Ni is a “waiting point” nucleus in the astrophysical rapid proton (rp) capture process Understanding the shell structure of this doubly-magic, N=Z=28 nickel nucleus is therefore of considerable interest for both nuclear structure and astrophysics Study nucleon transfer reactions in inverse kinematics: 56 Ni(p,d) 55 Ni at 37 MeV/A and 80 MeV/A to extract the neutron spectroscopic factor of 56 Ni and also its energy dependence 56 Ni(d, 3 He) 55 Co at 80 MeV/A to extract the proton spectroscopic factor of 56 Ni These two reactions allow us to compare the neutron and proton SF in the f 7/2 shell Extracted spectroscopic factors are important benchmarks in evaluating different pf-shell model interactions that may be used to predict the structure of 78 Ni, a major waiting point in the path of the r-process. Goal of experimental study Ground-state neutron SF of Ni isotopes Measurement of the SF is essential in calibrating the theoretical shell model of the nucleus. Two possible shell structures of 56 Ni: Inert core of 56 Ni with 28 protons and 28 neutrons inside Inert core of 40 Ca with 8 protons and 8 neutrons outside IPM S800 Spectrograph Spectroscopic Factors from Transfer Reactions with Radioactive Beams 1.5mm Si 65μm Si CsI(Tl) HiRA PID - 56 Ni(d, 3 He) 55 Co 3 He Summary Implications: 56 Ni is not a good core Accurate description of Ni isotopes requires full model space with 40 Ca core. GXPF1A describes the data better than K3B interactions Reaction Model: (d/d) RM calculated from 3-body model with global optical potentials and standard geometry of n-wave functions. The probe: Spectroscopic Factor N=2 N=8 N=20 N=28 Single-nucleon transfer reactions are a powerful tool to study single particle states. Spectroscopic Factor (SF) quantifies the nature and occupancy of the single particle orbits in a nucleus. SF provides information on nuclear structure and is a key input for astrophysics calculations. RM d d Exp d d Exp SF Lab Angle [degrees] Differential Cross section [arb. units] 0 20 40 60 (d, 3 He) @ 80.7 MeV/A Shape of calculation section depends on potentials. Best match to data is for CH89 (p), Perey-Perey (d), and Bechetti- Greenlees ( 3 He). Deuteron Potentials: pp = Perey-Perey ADNTD 17 (1976) 3 H e P o t e n t i a l s : g d p = G D P 0 8 P R C 7 9 ( 2 0 0 9 ) 0 2 4 6 1 5 a n d c h = C h a p e l H i l l 8 9 b g = B e c h e t t i - G r e e n l e e s A D N T D 1 7 ( 1 9 7 6 ) (p,d) @ 80.7 MeV/A 0 20 40 0 20 40 10 30 Differential Cross section [arb. units] D e u t e r o n P o t e n t i a l s : p p = P e r e y - P e r e y A D N T D 1 7 ( 1 9 7 6 ) j s = J o h n s o n - S o p e r P R C 1 ( 1 9 7 0 ) 9 7 6 Proton Potential: ch = Chapel Hill 89 Phys. Rep. 201 (1991) 57 Lab Angle [degrees] (p,d) @ 37 MeV/A SF is extracted by matching the magnitude of the calculated cross section to the data The value SF exp = 7 was determined for the f 7/2 neutron from data at 37 MeV/A js = Johnson-Soper PRC 1 (1970) 976 *Note: there seems to be a shift in angle between the data and calculations which is not yet understood
description
1.5mm Si. CsI(Tl). 65 μm Si. Spectroscopic Factors from Transfer Reactions with Radioactive Beams. R. Shane 1* , T . K. Ghosh 2 , A . Sanetullaev 1 and M. B. Tsang 1 For the HiRA Collaboration. N=28. N=20. Experimental Setup. 56 Ni: An alluring nucleus. - PowerPoint PPT Presentation
Transcript of 55 Co
The NSCL is funded in part by the National Science Foundation and Michigan State University.
55Co
S800 PID - 56Ni(d,3He)55Co
Target (p / d)
56Ni Beam
Φ To S800Spectrograph
55Ni / 55Co (measure P,E, )Φ
MCP's
θ
d / 3HeHiRA
Results
Experimental Setup
Inverse kinematics at 37MeV/A,
80MeV/A
R. Shane1*, T. K. Ghosh2, A. Sanetullaev1 and M. B. Tsang1
For the HiRA Collaboration
1National Superconducting Cyclotron Laboratory, Michigan State Univ., East Lansing, MI 48824, USA2Variable Energy Cyclotron Centre, 1/AF, Bidhannagar, Kolkata 700064, India
* E-mail: [email protected]
The global OM potentials obtained from systematic analysis of (p,d) and (d,p) transfer reactions at low-energy do not seem to work at higher energy. Work on extraction of the neutron and proton SF from the higher-energy data, as well as a consistent framework for comparison to the low-energy results, is in progress.
HiRA + S800 @NSCL
High Resolution Array (HiRA)
56Ni: An alluring nucleus 56Ni is outside the valley of stability and is doubly magic according to the Independent Particle Model (IPM)
In the shell model, the magic number 28 is the first shell that requires the introduction of a strong spin-orbit interaction
56Fe is the most abundant heavy element in the universe, yet 56Ni is the first doubly-magic nucleus that is not stable
56Ni is a “waiting point” nucleus in the astrophysical rapid proton (rp) capture process
Understanding the shell structure of this doubly-magic, N=Z=28 nickel nucleus is therefore of considerable interest for both nuclear structure and astrophysics
Study nucleon transfer reactions in inverse kinematics:
56Ni(p,d)55Ni at 37 MeV/A and 80 MeV/A to extract the neutron spectroscopic factor of 56Ni and also its energy dependence
56Ni(d,3He)55Co at 80 MeV/A to extract the proton spectroscopic factor of 56Ni
These two reactions allow us to compare the neutron and proton SF in the f7/2 shell
Extracted spectroscopic factors are important benchmarks in evaluating different pf-shell model interactions that may be used to predict the structure of 78Ni, a major waiting point in the path of the r-process.
Goal of experimental study
Ground-state neutron SF of Ni isotopes
Measurement of the SF is essential in calibrating the theoretical shell model of the nucleus.
Two possible shell structures of 56Ni:
Inert core of 56Ni with 28 protons and 28
neutrons inside
Inert core of 40Ca with 8 protons and 8 neutrons
outside
IPM
S800 Spectrograph
Spectroscopic Factors from Transfer Reactions with Radioactive Beams
1.5mm Si
65 m μ SiCsI(Tl)
HiRA PID - 56Ni(d,3He)55Co
3He
Summary
Implications: 56Ni is not a good core Accurate description of Ni isotopes requires full model space
with 40Ca core. GXPF1A describes the data better than K3B interactions
Reaction Model:
(d/d)RM calculated from 3-body model with global optical potentials and standard geometry of n-wave functions.
The probe: Spectroscopic Factor
N=2
N=8
N=20
N=28
Single-nucleon transfer reactions are a powerful tool to study single particle states.
Spectroscopic Factor (SF) quantifies the nature and
occupancy of the single particle orbits in a nucleus.
SF provides information on nuclear structure and is a key input for
astrophysics calculations.
RMdd
Expdd
ExpSF
Lab Angle [degrees]
Diff
ere
nti
al C
ross
sect
ion [
arb
. unit
s]
0 20 40 60
(d,3He) @ 80.7 MeV/A
Shape of calculation section depends on potentials. Best match to data is for CH89 (p), Perey-Perey (d), and Bechetti-Greenlees (3He).
Deuteron Potentials:pp = Perey-Perey
ADNTD 17 (1976)
3He Poten
tials:gdp = G
DP08
PRC 79 (2009) 024615
and ch=Chapel Hill 89
bg = Bechetti-G
reenlees A
DN
TD
17 (1976)
(p,d) @ 80.7 MeV/A
0 20 400 20 4010 30
Diff
ere
nti
al C
ross
sect
ion [
arb
. unit
s]
Deu
teron Poten
tials:pp = Perey-Perey
AD
NT
D 17 (1976)
js = Johnson-SoperPR
C 1 (1970) 976
Proton Potential:ch = Chapel Hill 89
Phys. Rep. 201 (1991) 57
Lab Angle [degrees]
(p,d) @ 37 MeV/A
SF is extracted by matching the magnitude of the calculated cross section to the data
The value SFexp = 7 was determined for the f7/2 neutron from data at 37 MeV/A
js = Johnson-SoperPRC 1 (1970) 976
*Note: there seems to be a shift in angle between the data and calculations which is not
yet understood
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