Mass Measurements for Short-lived Nuclei at CSRe-Lanzhou Meng Wang Institute of Modern Physics, CAS The 9th Japan- China Joint Nuclear Physics Symposium (JCNP 2015)

H. S. Xu, Y. H. Zhang, M. Wang, R. J. Chen, X. C.Chen, C. Y. Fu, B. S. Gao, P. Shuai, M.Z. Sun, X. L.Tu, Y.M. Xing, X. Xu, X. L. Yan, Q. Zeng, X. H. Zhou, Y. J. Yuan, J. W. Xia, J. C. Yang, Z. G. Hu, X. W. Ma, R. S. Mao, B. Mei, G. Q. Xiao, H. W. Zhao, T. C. Zhao, W. L. Zhan (IMP-CAS, Lanzhou, China) Yu.A. Litvinov, S.Typel (GSI, Darmstadt, Germany) K. Blaum (MPIK, Heidelberg, Germany) Y. Sun (Shanghai Jiao Tong University, Shanghai, China) Baohua SUN (Beihang University) H. Schatz, B. A. Brown (MSU, USA) G. Audi (CSNSM-IN2P3-CNRS, Orsay, France) T. Yamaguchi (Saitama University, Saitama, Japan) T. Uesaka, Y. Yamaguchi (RIKEN, Saitama, Japan) CSRe mass measurement collaboration

Outline Motivation and background Method and technical improvements Results and discussions Perspective and summary

= N× +Z× － binding energy Mass → binding energy → interaction Motivation: why do we measure nuclear masses? Filed of applicationRequired uncertainty Chemistry: identification of molecules10 −5 –10 −6 Nuclear physics: shells, sub-shells, pairing10 −6 Nuclear fine structure: deformation, halos10 −7 –10 −8 Astrophysics: r-process, rp-process, waiting points10 −7 Nuclear models and formulas: IMME10 −7 –10 −8 Weak interaction studies: CVC hypothesis, CKM unitarity10 −8 Atomic physics: binding energies, QED10 −9 –10 −11 Metrology: fundamental constants, CPT10 −10 √ √ √ K. Blaum, Physics Reports 425 (2006) 1–78

predicted ~7000 discovered ~3200 mass known ~2400 Background: current status of mass measurements

IMP RIKEN ANL MSU TRIUMP FSU GSI JYFL CERN GANIL MSL JGU JINR LBL ORNL CIAE IAEA BNL Main institutions of nuclear research Facilities for direct mass measurements Background: worldwide activities Monday 14:00-14:30, Yoshitaka Yamaguchi, Commissioning of the rare-RI ring at RIKEN RI Beam Factory Monday 14:50-15:10, Peter Schury, MRTOF mass measurements at GARIS-II: Toward SHE identification via mass spectroscopy

CSRe CSRm 1000 AMeV (H.I.),  2.8 GeV (p) RIBLL1 RIBs at tens of AMeV RIBLL2 RIBs at hundreds of AMeV Research aims: establish the IMS technique; measure nuclear masses; study the associated physics Background: HIRFL-CSR research facility Heavy Ion Research Facility in Lanzhou

Method and technical improvements Principle Resolving power Double ToF Charge discrimination

DT TOF detector CSRe CSRm SFC SSC Procedure of mass measurements

T=L/v Bρ=m/q βγc Principle

T=L/v Bρ=m/q βγc Principle : isochronous mass spectrometry

arXiv: Correction for drift of the magnetic fields

Resolving power ps

Principle of double-TOF IMS Revolution time (ns) Relative velocity (%)

Double-TOF IMS Two ToF detectors: ds=18 m Singal TOF Doubel TOF

34 Ar & 51 Co close m/q Charge & Frequency Resolved IMS

PL B 735 (2014) 327 Charge & Frequency Resolved IMS

Results and discussions Overview Impact on rp-process Impact on ν p-process In-ring decay

First mass measurement at CSRe M. Wang et al., Int. J. Mod. Phys. E, Vol. 18, No. 2 (2009)

Beams: 78 Kr, 58 Ni, 86 Kr, 112 Sn, 58 Ni, 36 Ar Double TOF Improved precision Measured first time X. L. Tu et al., PRL 106, (2011) Y. H. Zhang et al., PRL 109, (2012) X. L. Yan et al. ApJ 766, L8 (2013) P. Shuai et al., PL B 735,327 (2014) H. S. Xu et al., IJMS 349, 162 (2013) Precision ~10 -7 ( keV) Overview of experimental results Monday 14:30-14:50, Xinliang Yan, Direct mass measurements of 58 Ni projectile fragments at CSRe

Mass values of short-lived nuclei are important input parameters to study rp-process Companion star Neutron star X-ray burst R. Giacconi 2002 Nobel rp-process in astrophysics

Waiting points: Reaction path Light curve Element abundance 65 As S p ( 65 As) >-250 keV (AME2003) Waiting point at 64 Ge in the Type I X-ray burst ? Results from CSRe: (1) waiting point 64 Ge

S p ( 65 As) = -90 (85) keV  Light curve of Type I x-ray burst 89%–90% of the reaction flow passes through 64 Ge via proton capture indicating that: 64 Ge is not a significant rp-process waiting point. 11 Abundance of burst ashes X.L. Tu et al., PRL 106, (2011) Results from CSRe: (1) waiting point 64 Ge

p-nuclei …… The uncertainty in the nuclear mass of 82 Zr can lead to a factor of two reduction in the abundance of the p-isotope 84 Sr. ν p-process as the origin of p-nuclei

Results from CSRe: (2) p-process The reaction path of vp-process is uncertain due to unknown masses AME2003

CSR result Results from CSRe: (2) p-process The reaction path of vp-process at A=80-86 is determined AME2012

T 1/2 = 71 ms Ex=2645 keV 94m Ru In-ring decay of T 1/2 = 71  s Isomer in 94 Ru Neutral atombare atom internal conversion coefficient α=0.335 T 1/2 ?

T 1/2 = 71  s Ex=2645 keV 94m Ru In-ring decay of T 1/2 = 71  s Isomer in 94 Ru Decay point Revolution time obtained from 30 turns In progress

Perspective and summary next experiment summary

Next experiment Ex Next week Primary beam: 112 Sn Aim 1: mass of 101 In and Ex of 101m In. Aim 2: Masses of: 89 Ru, 91 Rh, 93 Pd

Tc Ru Rh Pd Ag Thank you!