Neutron-Proton Asymmetry Dependence of Spectroscopic Factors Jenny - - PowerPoint PPT Presentation

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

• rbitals

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 &

• verlap 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(expt)/SF(theory)

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(expt)/SF(theory)

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

SF(expt)/SF(theory)

Projectile (fast beam) Target

Core re

9Be or 12 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) 𝝉 (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 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

• f reaction model at low-energy

Direc ect 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

SF(expt)/SF(theory)

• 2. Inert-core ?

Intranuclear Cascade Model (INC)

Mult ltip iple le scat atter ering ing/ Evapo apora ratio ion Core re excit itat atio ion

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(14O13O* to p-decay)

Invariant mass spectrum (13O*)

p + 12N13O*

13O*p+12Ng.s.

σ< 2.0 (14) mb

Invariant mass spectrum (13O*)

p + 11C12N* p + p+ 11C 13O*

13O*11C+p+p

σ < 2.6(14) mb

p+p+11C Triple-coincidence events p1 + 11C12N* p2 + 11C12N*

14O13O* , 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”

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

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 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