neutron-proton asymmetry dependence of spectroscopic …

Jenny Lee

Neutron-Proton Asymmetry

Dependence of Spectroscopic Factors

The University of Hong Kong

JCNP Symposium

Nov 7-12, 2015

Hong Kong

Tokyo

Hong Kong

Beijing

Shanghai

HIAF

惠州Huizhou

~ 100 km

First Nuclear Physics

Group in 2014

University of Hong Kong

International Workshop on Neutron-Proton

Correlations & 12th RIBF Discussion July 7-12, 2015

The University of Hong Kong

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

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)

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

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

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

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

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

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 ?

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

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%

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)

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

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

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

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

30Ne: |ΔS| ~ 20 MeV 12C(30Ne, 29Ne)X

~230 AMeV


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

Direct KO

Knockout Reaction Mechanism

NSCL, MSU - 14O knockout at 60 MeV/A


Understanding the knockout

reaction mechanism needed !

INC: Significant core-excitation process

depletes the one-neutron removal channel

14O(d,t)

Rs=sexp/stheo


ΔS=Sn-Sp (MeV)


S

F(e

xp

t)/S

F(t

heo

ry)

2. Inert-core ?

Intranuclear Cascade Model (INC)

Multiple scattering/

Evaporation

Core excitation

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

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

p

Completed in Oct 2013

RIKEN: Hodoscope

Peking University: Si Array

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

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

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)

Invariant mass spectrum (13O*)

p + 12N13O*

13O*p+12Ng.s.

σ< 2.0 (14) mb

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*

14O13O* , σ < 4.6(20) mb

Y. Sun, JL et al., paper in preparation


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”


NSCL, MSU - 14O knockout at 60 MeV/u


13O

Large Asymmetry in

Parallel Momentum Distribution

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

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


Large discrepancy not due to

reaction energy being too low for

Eikonal model description

Reaction mechanism described by

INC model is studied

30Ne


neutron-proton asymmetry dependence of spectroscopic …

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