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Jenny Lee
Neutron-Proton Asymmetry
Dependence of Spectroscopic Factors
The University of Hong Kong
JCNP Symposium
Nov 7-12, 2015
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Hong Kong
Tokyo
Hong Kong
Beijing
Shanghai
HIAF
惠州Huizhou
~ 100 km
First Nuclear Physics
Group in 2014
University of Hong Kong
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International Workshop on Neutron-Proton
Correlations & 12th RIBF Discussion July 7-12, 2015
The University of Hong Kong
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HKU Group Members
Jenny Lee Zhengyu Xu
(Postdoc)
Ph.D. Univ. of Tokyo
Yelei Sun
(Research Assistant)
Ph.D. Peking Univ.
Sylvain Leblond
(Postdoc)
Ph.D. Univ. of Caen
Jiajian Liu
(PhD student)
M.S. Shenzhen Univ.
Taras Lokotko
(PhD student)
M.S. Univ. of Paris
External Members
for Data Analysis
Hongna Liu
(PhD student, Peking Univ.)
Xinxing Xu
(Postdoc)
Ph.D. CIAE
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Nuclear Experimental Programs @ HKU
Correlation Effect on a Nucleon (Direct Reactions)
• One-nucleon knockout at 250 MeV/u (RIKEN, JL et al., paper in preparation)
• Knockout of 14O at 60 MeV/u (RCNP, Y. Sun et al., paper in preparation)
• (p,d) Transfer of 34,46Ar at 70 MeV/u (MSU, J. Manfredi, data in analysis)
Neutron-Proton Correlations (Direct Reactions)
• Systematic np- & nn- transfer reactions on sd-shell nuclei (RCNP, Y. Ayyad et al., paper in prep)
• Exclusive np-knockout of 12C at 200 MeV/u (RIKEN, H. Liu et al., paper in preparation)
• (p,pNN) at GeV (IMP, Lanzhou, Proposal)
Alpha-cluster Correlations (Direct Reactions)
• (p,p α) of neutron-rich Be (RIKEN, T. Lokotko PhD)
Nuclear Structure (in-beam gamma spectroscopy)
• 30Ne (RIKEN, H. Liu et al., paper in preparation)
• 53,55,56Ca (RIKEN, J. Liu PhD)
• 77Ni (RIKEN, Z. Xu et al., paper in preparation)
• 69,71,73Co (RIKEN, T. Lokotko, data in analysis)
• 100Sn (RIKEN, Proposal)
Nuclear Structure
(β-dacay spectroscopy)
• 173,174Er (RIKEN, J. Liu in analysis)
Detectors: DALI2 upgrade
(60 NaI(Tl) detectors)
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Nucleon Correlations
Truncated shell model space
+ effective interactions
Few active
orbitals
High
Occupancy
Inert Core Inert Core
Greater
distribution of
nucleons to
higher energy
configuration
Reduction in
Occupancy
Short-range,
tensor &
collective
correlations
In reality
Removing nucleon from occupied orbital
Cross sections (probability) depend on the single-particle occupancy &
overlap of many-body wave functions
Probing the nuclear wave function
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Spectroscopic Factor (SF)
(e,e’p) reactions
(e,e’p) – Stable nuclei (near closed shell)
• Constant ~30-40% of SF reduction compared to theory
• Correlations missing in interactions used in SM
L. Lapikas, Nucl. Phys. A553, 297c (1993)
How much ? What is the Isospin
Dependence of nucleon correlations?
How good the effective interaction in
Shell Model can describe the correlations ?
SM description is accurate
Some correlations missing in the interactions ?
Extend SF measurements to Exotic Nuclei !
Cross Sections Reaction Model
Spectroscopic Factors (expt)
Quantify Occupancy Correlation Effects
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Knockout reactions: Yes & Strong
Transfer reactions: Weak
Q: Isospin Dependence ?
Systematic difference
between two probes !
Incompatibility Incomplete understanding in underlying reaction mechanism
SF
(ex
pt)
/SF
(th
eory
) Isospin Dependence of Shell Occupancies?
J. Lee et al., Phys. Rev. Lett 104, 112701 (2010)
A. Gade et al., Phys. Rev. Lett. 93, 042501 (2004)
Phys. Rev. C 77, 044306 (2008) & reference therein
Transfer Reaction
NSCL: 34,46Ar(p,d) at 70 A MeV
- same energy as knockout reactions for direct comparison
p(34,36,46Ar,d) at 33 A MeV
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Primary Devices
CH2
34,46Ar Beam
34, 46Ar + p →d + 33, 45Ar @ 70 MeV/u
Φ To S800 Spectrograph
33, 45Ar
P,E,Φ
2. S800 Spectrograph
θ
deuteron
1. High Resolution Array (HiRA)
Transfer Reactions for Correlation Studies
National Superconducting Cyclotron Laboratory
Michigan State University
East Lansing, Michigan, USA
3. Multi-Channel Plates (MCP)
Completed in December 2014
(analyzed by Juan Manfredi)
MCP
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Knockout reactions: Yes & Strong
Transfer reactions: Weak
Q: Isospin Dependence ?
Systematic difference
between two probes !
Incompatibility Incomplete understanding in underlying reaction mechanism
SF
(ex
pt)
/SF
(th
eory
) Isospin Dependence of Shell Occupancies?
J. Lee et al., Phys. Rev. Lett 104, 112701 (2010)
A. Gade et al., Phys. Rev. Lett. 93, 042501 (2004)
Phys. Rev. C 77, 044306 (2008) & reference therein
Knockout Reaction ?
Transfer Reaction
NSCL 09084: 34,46Ar(p,d) at 70 A MeV
- same energy as knockout reactions for direct comparison
p(34,36,46Ar,d) at 33 A MeV
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Knockout Reaction Mechanism
NSCL, MSU - 14O knockout at 60 MeV/u
F. Flavigny et al., Phys. Rev. Lett. 108, 252501 (2012)
14O(d,t)
Rs=sexp/stheo
Weakly-bound Deeply-bound
ΔS=Sn-Sp (MeV)
Reactions ~ 70 MeV/u
S
F(e
xp
t)/S
F(t
heo
ry)
Projectile (fast beam)
Target
Core
9Be or 12C
Reaction Theory:
Eikonal & Sudden Approximations
J. Tostevin et al., J. Phys. G, Part. Phys. 25, 735 (1999)
Data at energies of 200-300 MeV/A
1. Invariant with beam energy ?
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Univ. of Surrey
J. A. Tostevin, E.C. Simpson
Tokyo Tech.
Y. Kondo, N. Kobayashi, T. Nakamura
Theory Collaboration:
CNS/ Unvi. Of Tokyo
S. Michimasa
One Nucleon Knockout Reaction on 30Ne @ 230 MeV/u
RIKEN H. Liu, J. Lee, P. Doornenbal, H. Scheit, S. Takeuchi, N. Aoi, K. Li,
M. Matsushita1, D. Steppenbeck1, H. Wang, H. Baba, E. Ideguchi,,
T.Motobayashi, H. Sakurai, M. Takechi, Y. Togano
RCNP/Osaka University
K. Minomo, K, Ogata
JAEA
Y. Utsuno
Hokkaido University
M. Kimura
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BigRIPS (Beam PID)
ZDS: ZeroDegree
Spectroscometer
(fragment PID &
momentum measurement)
DALI2
(γ-ray
detection)
1N-Knockout of nuclei with large ΔS at 230 AMeV
Beam: 30Ne @ ~ 230 A MeV
1n-knockout : 30Ne 29Ne
1p-knockout : 30Ne 29F
30Ne: |ΔS| ~ 20 MeV
12C target
2.54g/cm2
9Be
target
(15mm)
48Ca beam
345MeV/u
~75pnA
30Ne 228MeV/u ~440 cps Purity: 63%
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Beam
Target
Reaction
Product
γ-ray
γ detection Array - DALI2
• 186 NaI(Tl) detectors
• θ coverage 11° to 165°
• ∆E/E ≈ 11 % at 250 MeV/u
• ≈ 20 % FEP efficiency at 1MeV
S. Takeuchi et al., NIMA. 763, 596 (2014)
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Gamma Spectrum of 29F & Cross Sections
Inclusive σ: 5.8 (3) mb
Ground-state σ: 5.2 (3) mb γ-energy threshold: 200 keV
P. Doornenbel et al., paper in preparation
SM: sd-pf model space with the SDPF-M
effective interaction (Y. Utsuno)
AMD: Antisymmetrized molecular dynamics
with Gogny D1S interaction (M. Kimura)
ZDS
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Gamma Spectrum of 29Ne
Fit function: Response functions(GEANT4)
+ Exponential background
*Difference between fitting results with & without C
excitation Systematic error
C excitation
12C(30Ne,29Ne + γ) X
SeGA @ NSCL
Published in NNDC
232(6)
622(4)
931(8)
Counts/ 10keV
35
15
ZDS
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Gamma Spectrum & Cross Sections
γ-energy threshold: 200 keV
γ-γ coincidence analysis: direct transition to “g.s.”
Elevel
(keV)
𝝈 (mb)
Inc. 62(2)
< 200 25(4)
231 11(2)
625 24(2)
923 2.2(0.4)*
* Lower limit
H. Liu, JL et al., paper in preparation
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Comparison to Theoretical Cross Sections ERT: Eikonal reaction theory with an extension of the continuum-
discretized coupled-channels method (CDCC) K. Minomo, K. Ogata
M. Yahiro et al., Prog. Theor. Phys. 126, 167-176 (2011), Prog. Theor. Exp. Phys. 2012, 01A206 (2012).
K. Minomo et al., Phys. Rev. C 90, 027601 (2014)
29F: g.s. σ: 5.2 (3) mb Rs=0.31 (SM) and 0.54 (AMD)
Assuming g.s. 3/2+
Rs = 0.51 (SM) and 0.36 (AMD)
Assuming g.s. 3/2-
Rs = 0.59 (SM) and 0.39 (AMD)
29Ne: σ (<200 keV) : 25 (4) mb
P// 3/2+ : 14 mb, 3/2- : 11 mb
Rs=σexp/σ theo
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30Ne: |ΔS| ~ 20 MeV 12C(30Ne, 29Ne)X
~230 AMeV
Weakly-bound Deeply-bound
Rs=sexp/stheo
Both SM & AMD over-predict
g.s. SFs interactions need to
be improved
12C(30Ne, 29F)X
~230 AMeV
Assuming
g.s. 3/2+
Large Reduction as data <90 AMeV
Discrepancy not due to invalidity
of reaction model at low-energy
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Direct KO
Knockout Reaction Mechanism
NSCL, MSU - 14O knockout at 60 MeV/A
F. Flavigny et al., Phys. Rev. Lett. 108, 252501 (2012)
Understanding the knockout
reaction mechanism needed !
INC: Significant core-excitation process
depletes the one-neutron removal channel
14O(d,t)
Rs=sexp/stheo
Weakly-bound Deeply-bound
ΔS=Sn-Sp (MeV)
Reactions ~ 70 MeV/u
S
F(e
xp
t)/S
F(t
heo
ry)
2. Inert-core ?
Intranuclear Cascade Model (INC)
Multiple scattering/
Evaporation
Core excitation
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Experiment at RCNP, Osaka University (Japan)
RIKEN
J. Lee, H . Liu, G. Lorusso, S. Nishimura, S. Takeuchi, J. Wu, Z. Xu
Peking University
Y. Ye, J. Chen, Y. Ge, Z. Li, J. Lou, R. Qiao, Y. Sun
RCNP
N. Aoi, Y. Ayyad, T. Hashimoto, E. Ideguchi, H.J. Ong, J. Tanaka, M. Tanaka,
T. Trong, H. Suzuki, T. Yamamoto
Y. Sun, J. Chen (PKU) – Support (local + travel expense) by RCNP Young-
Researcher Program + Supervision during 8-month / 3-month stay at RCNP
Studies of Single-Nucleon Correlations
using Knockout Reactions
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14O + 12C 13N + p
13O + n
12N + p
11C + 2p
Study of Reaction Mechanism
Fully Exclusive Measurements of reaction products
大阪大学・核物理研究中心
Osaka University Research
Center for Nuclear Physics
K140 AVF Cyclotron
K400 Ring Cyclotron
pol p 400 MeV 3He 140 AMeV
Light heavy ion 100 AMeV
EN-Course Beam line
p
Si Array
Hodoscope
RIKEN: Hodoscope
Peking University: Si Array
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p
Completed in Oct 2013
RIKEN: Hodoscope
Peking University: Si Array
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Silicon Detection Array
32-strip double-sided silicon detector 1024 pixels
2 mm strip width excellent position resolution
4 CsI(Tl) crystals for total energy measurement
PKU-made Preamplifier by
Dr. Yucheng Ge
Electronics (~500 Channels)
RIKEN-made Preamplifier
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Hodoscope and Tube Chamber
42 Scintillators (1-meter long)
3 layers (active area of 1x1 m2)
∆E : 5 mm thick (13 bars)
E1, E2: 60 mm thick
Between Target to Hodoscope:
3.6 meters in vacuum
Position & Energy resolution
Hodoscope Acceptance: 0°-7°
T. Motobayashi &
Rikkyo University group
Y. Sun, Ph.D Thesis 2015,
paper in preparation
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Particle Identification in Hodoscope by ΔE-TOF and E-TOF
Knockout of 14O on C target at 60 MeV/u
breakup in uniform
phase space
>2.1MeV
>1.5MeV
>2.5MeV
①
②
③
Sn = 23.2 MeV
Sn > 23.2 MeV
Coincidence Measurement of Residues and Decayed Protons
Core-excitation Strength:
σ(14O13O* to p-decay)
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Invariant mass spectrum (13O*)
p + 12N13O*
13O*p+12Ng.s.
σ< 2.0 (14) mb
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Invariant mass spectrum (13O*)
p + 11C12N*
p + p+ 11C 13O* 13O*11C+p+p
σ < 2.6(14) mb
p+p+11C Triple-coincidence events
p1 + 11C12N*
p2 + 11C12N*
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14O13O* , σ < 4.6(20) mb
Y. Sun, JL et al., paper in preparation
Knockout of 14O on C target at 60 MeV/u
13O*p+12Ng.s. σ< 2.0 (14) mb
13O*12N*11C+p+p σ < 2.6(14) mb
11C inclusive σ = 60(9) mb
INC Calculation:
σ 13O (gs): 15.8 mb (while Eikonal model: 57.6 mb)
σ 11C: 66 mb, mainly from “ Core-excitation channels of 13O”
Data:
σ 13O (gs): 13 mb
σ 11C: 60 (9) mb, but only 4.6 (20) mb from “Core-excitation”
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Knockout of 14O on C target at 60 MeV/u
NSCL, MSU - 14O knockout at 60 MeV/u
F. Flavigny et al., Phys. Rev. Lett. 108, 252501 (2012)
13O
Large Asymmetry in
Parallel Momentum Distribution
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14O(p,pN) at 100 MeV/u
K. Ogata et al., Phys. Rev. C 92, 034616 (2015)
DWIA
Solid Hydrogen
target
13O ,13N
Proposed by Y. Sun
to RIKEN PAC-16
Investigate reaction mechanism
Probe origin of reduction in SF & asymmetric P//
Reaction model for reliable structure information
Parallel Momentum Distribution
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Knockout of 14O on C target at 60
MeV/u (RCNP, Osaka University)
Y. Sun et al. paper in preparation
Single-nucleon Knockout of 30Ne
at 230 MeV/u (RIKEN)
H. Liu et al., papers in preparation
Summary : Neutron-Proton Asymmetry
Dependence of Spectroscopic Factors
(p,pN) of 14O at 100 MeV/u (RIKEN), DWIA Model
Proposed by Y. Sun
Weakly-bound Deeply-bound
Large discrepancy not due to
reaction energy being too low for
Eikonal model description
Reaction mechanism described by
INC model is studied
30Ne
Reactions ~ 70 MeV/u