1. Direct mass measurement of 58 Ni projectile fragments at CSRe Xinliang Yan Precision nuclear spectroscope group Institute of Modern Physics, Chinese Academy of Sciences (1)Motivation (2)Experiment (3)Mass of 45 Cr and Ca-Sc cycling (4)Summary & outlook

2. Motivation of the experiment A.Langmeier, et al., APJ 323, 288(1986) H. Schatz, Int. J. Mass Spectrom. 349–350, 181 (2013). 2 X-ray burst and rp-process 58 Ni T 1/2 >10 -23 secs

3. 3 Isochronous mass spectrometry at CSRe H.S. Xu et al., Int. J. Mass Spectrom. 349–350, 162 (2013). Border of known mass 10 8 ppp, every 24 secs

4. CSRe set on the isochronous mode (γ t =1.395) ~ 12 stored ions/injection ； DAQ for 200 μs In total 15808 injections (117 hours) 4 Isochronous mass spectrometry at CSRe X. L. Tu et al., Chinese Phys. C 34(3): 363(2010) Revolution-T ~ 580 ns – 650 ns 10 8 pps, every 24 secs

5. From raw data to revolution time spectrum 5 X. L. Tu et al. NIM A 654, 213 (2011).

6. Instability of CSRe-dipole magnet fields 6 X.L. Yan, PhD Thesis(2014) 40 ps4×10 -5

7. 7 Correction of the revolution-times X.L. Yan, PhD Thesis(2014)

8. The revolution time spectrum Revolution time (ns) … … 43 Ti 20 Na

9. The revolution time spectrum Revolution time (ns) … … 43 Ti 20 Na ΔRevTime=6.1(2) ps E*(CSRe) = 441(14) keV E*(AME) = 425.8(1)keV T 1/2 (atom)=130(3)ms

10. Mass calibration of the spectrum Revolution time (ns) … … 43 Ti 20 Na

11. Mass calibration results Y. H. Zhang, et al, Phys. Rev. Lett. 109, 102501 (2012) 11

12. （ 3 ） MASS OF 45 CR AND CA-SC CYCLING IN X-RAY BURSTS ME( 45 Cr)=−19515(20 statics ) keV 12 Tz=-3/2 The impact of the new masses on the modeling of rp-processes in X-ray bursts.

13. Isomer contamination in the 45 Cr RISING CSRe 13 (GSI) ME( 45 Cr)=−19515(20) keV  ME( 45 Cr)= −19515(35)keV R. Hoischen et al., J. Phys. G 38 (2011) 035104

14. Effects of the newly measured masses S p ±3 σ(S p ) [AME03] S p ±3 σ(S p ) [CSRe] NuclideCount Sp(AME03) （ keV ） Sp(CSRe) （ keV ） T(1/2) 41 Ti 76 2466(100)#2464(28)82.6(5)min 43 V 42 187(230)#83(43)79(2) ms 45 Cr 218 2139(514)2684(125)60.9(4) ms 47 Mn 119 75(161)#381(38)88(1) ms 49 Fe 338 2549(186)#2720(113)64.7(3) ms 53 Ni 651 2739(175)#3000(74)55.2(7) ms 55 Cu 19 -301(304)#-286(164)27(8) ms One-zone X-ray burst model (p, γ ) ↔(γ,p) equilibrium Recalculation of (γ,p) reactions 14

15. S p +3 σ(S p ) [AME03] S p -3 σ(S p ) [AME03] NuclideCount Sp(AME03) （ keV ） Sp(CSRe) （ keV ） T(1/2) 41 Ti 76 2466(100)#2464(28)82.6(5)min 43 V 42 187(230)#83(43)79(2) ms 45 Cr 218 2139(514)2684(125)60.9(4) ms 47 Mn 119 75(161)#381(38)88(1) ms 49 Fe 338 2549(186)#2720(113)64.7(3) ms 53 Ni 651 2739(175)#3000(74)55.2(7) ms 55 Cu 19 -301(304)#-286(164)27(8) ms Effects of the newly measured masses β+ decay (γ,p) rec. (p, γ) rec. (α,p) rec. (p,α) rec. Unstable Stable

16. Ca-Sc cycling reaction rate S p ± σ(S p ) [AME03] S p ± σ(S p ) [CSRe] X. L. Yan et al. APJ Lett 766, L8 (2013) 16 L. van Wormer et al., APJ 432, 326 (1994). F. Rembges, et al., APJ 484, 412 (1997).

17. Summary Direct mass measurement of proton-rich 58Ni fragments has been conducted in the CSRe. Maximum mass resolving power of 1.1×10 5 was achieved. Masses of series of Tz=-3/2 short-lived neutron-deficient nuclides including 41 Ti, 45 Cr, 49 Fe and 53 Ni were measured with a typical uncertainty of 30 keV. Y. H. Zhang, et al, Phys. Rev. Lett. 109, 102501 (2012). The new 45 Cr mass turned out to be essential for modelling the astrophysical rp-process. In particular, the formation of the predicted Ca- Sc cycle in X-ray bursts can be excluded. X. L. Yan et al. The Astrophysical Journal Letters 766, L8 (2013). The stability-improvement of the power supply for the CSRe dipole- magnets is still essentially needed. D-ToF isochronous mass spectrometry technique is under development at CSRe, aiming to improve the mass resolving power over the entire revolution time range in the spectrum. X. Xu, P. Shuai, R. Chen et al. (simulation).

18. 18 Further developments X.L. Yan, PhD Thesis(2014) P. Shuai, PhD Thesis (2015) X. Xu, PhD Thesis(2015) D-ToF IMS (simulated) Double ToFs D-ToF IMS (simulated)

19. The Collaborations 19 H.S. Xu, Y.A. Litvinov, H. Schatz, X. L. Tu, K. Blaum, X. H. Zhou, B. H. Sun, J. J. He, Y. Sun, M. Wang, Y. J. Yuan, J. W. Xia, J. C. Yang, G. Audi, G. B. Jia, Z. G. Hu, X. W. Ma, R. S. Mao, B. Mei, P. Shuai, Z. Y. Sun, S. T. Wang, G. Q. Xiao, X. Xu, T. Yamaguchi, Y. Yamaguchi, Y. D. Zang, H. W. Zhao, T. C. Zhao, W. Zhang, W. L. Zhan ， X.L. Yan, et al.

21. Challenges

22. Motivation of experiments 22 G. Audi, F. G. Kondev, M. Wang et al., Chinese Phys. C 36(12): 1157(2012)