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Mass Measurement Collaboration. G. Audi, K. Beckert, P. Beller, F. Bosch, D. Boutin, T. Buervenich, L. Chen, I. J. Cullen , B. Fabian, T. Faestermann, B. Franzke, H. Geissel, M. Hausmann, P. Kienle, O. Klepper, C. Kozhuharov, K.-L. Kratz, R. Knöbel, S.A. Litvinov,
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Mass Measurement Collaboration G. Audi, K. Beckert, P. Beller, F. Bosch, D. Boutin, T. Buervenich, L. Chen, I. J. Cullen, B. Fabian, T. Faestermann, B. Franzke, H. Geissel, M. Hausmann, P. Kienle, O. Klepper, C. Kozhuharov, K.-L. Kratz, R. Knöbel, S.A. Litvinov, Yu.A. Litvinov, Z. Liu, L. Maier, J. Meng, G. Münzenberg, F. Nolden, T. Ohtsubo, A. Ozawa, Z. Patyk, B. Pfeiffer, W.R. Plass, T. Radon, H. Schatz, C. Scheidenberger, J. Stadlmann, M. Steck, B. Sun, S. Typel, D.J. Vieira, P.M. Walker, H. Weick, M. Winkler, H. Wollnik, T. Yamaguchi and FRS-ESR collabration
Precise Mass Measurements of relativisticexotic Nuclei in Storage Rings Bao-Hua Sun • Introduction • High-precision mass spectrometry • Summary and Outlook
Motivation UNCLEAR PHYSICS NUCLEAR PHYSICS
Motivation Nuclear Mass M(N, Z) = Z·mp+ N·mp- B(N, Z)/c2 • Total Binding energies • Separation energy, drip-line • Shell, subshell closure, pairing • Deformation • New phenomena: decay mode, halo nuclei • New isomer, new isotope • Reaction Q-value • Test nuclear model or formula • … • Nuclear physics • Nuclear astrophysics • Others • Paths of nucleosynthesis • Element abundance • … • Fundamental interactions and Standard-Model • Metrology: fundamental constants, Kg .. • …..
Nuclear Chart AME’2003 Up to 2003
Mass Accuracy < 100 keV required
Half-lives T<0.1s
Worldwide Mass spectrometry K.Blaum,Phys.Rep.425,1(2006)
Facility Technique Production Separation Mass Resolving Power Mass Accuracy [keV] Measurement Duration SPEG GANIL B-TOF Spectrometer Fragmentation In-Flight 104 100 – 1000 ~ 1 s FRS-ESR IMS, GSI Storage Ring Isochronous Fission, Fragmentation In-Flight 2*105 ~ 100 ~ 50 s CSS2 GANIL Cyclotron Fusion, Fragmentation 3·104 50 – 1000 ~ 50 s MISTRAL CERN RF Spectrometer ISOL ~105 10 – 20 ~ 30 ms FRS-ESR SMS, GSI Storage Ring Schottky Fission, Fragmentation In-Flight ~ 2·106 5 - 30 ~ 5 s ISOTRAP CERN Penning Trap ISOL 106 – 107 10 ~ 1 s Mass Spectrometry Mass Accuracy Half-live limitation
GSI Accelerator Facility Today Up to 1000 MeV/u U92+ 2*109 pps SIS 11.4 MeV/u U73+ IonSources FRS UNILAC SHIP 238U4+ ESR Reaction Setup LAND - ALADIN Experimental Areas
Pereira et al., PRC 75, 14602(2007) Production & Separation of Exotic Nuclei Primary beams @ 400-1000 MeV/u Projectile fragmentation and fission Highly-Charged Ions (0, 1, 2 … bound electrons) In-Flight separation within ~ 500 ns Cocktail or mono-isotopic beams Transmission to the ESR of about 1%
Time-resolved SMS 1987 - B. Franzke, H. Geissel, G. Münzenberg
Principle of electron cooling electron collector electron gun high voltage platform electron beam magnetic field before cooling after cooling ion beam ion intensity 1.03 0.97 1 rel. ion velocity v/v0 The idea of electron cooling is a heat exchange through Coulomb scattering between hot heavy particles (antiprotons) and cold electrons while the beams are mixed in a cooling section. Same mean velocity of e- and ions; strong magnetic guiding field; substitution of e- after a cycle
Electron cooler The 250 keV electron cooler at the ESR
Characteristic of Time-resolved SMS SMS Sensitivity to single ion discovery of new isomer, new isotope B. Sun et al., EPJA 31 (2007) 393
Characteristic of Time-resolved SMS SMS Sensitivity to single ion discovery of new isomer, new isotope Time-correlated measurement identification, mass, lifetime Lifetime = 193 s As complimentary tools to g-ray spectrometry
Characteristic of Time-resolved SMS SMS Sensitivity to single ion Time-correlated measurement High precision: 10-7-10-8 93Tc42+ and 93gMo42+ as references:: ME(93Tc)=-83603(4) keV; ME(93gMo)=-86803(4) keV to determine the mass of 93mMo42+ By restricting over a small frequency range we minimize ion-optical nonlinearities and achieve the mass accuracy of m/m=4.3*10-8 for A=93. H. Geissel et al., Eur. Phys. J. Special Topics (2007)
Characteristic of Time-resolved SMS SMS Sensitivity to single ion Time-correlated measurement High precision: 10-7-10-8 Large-scale mass measurements
Isochronous Mass Spectrometry 1985 - H. Wollnik, Y. Fujita, H. Geissel, G. Münzenberg,et al.
RTOF=60 000 Revolution time spectrum About 13% in mass-over-charge range m/q range: 2.4-2.7 Nuclei with half-lives as short as 17 s
17 s isomeric state in 133Sb RIMS=200 000 Expected half-live of bare isomer: ~ 17 ms, t~991 Genevey et al., EPJA 7, 463 (2000) IMS: resolving power (FWHM)
Z N Characteristic of IMS IMS Sensitivity to single ion High precision: ~10-6 Large-scale mass measurements B.Sun et al., NPA 812 (2008)1
Shell evolution at N=50 Independent experimental information
Influence on the r-process calculation nn=1020cm-3, T=1.5*109 K
Experimental proton-neutron interaction p-n interactions are sensitive to the spatial overlaps Of the proton and neutron wave functions
Experimental proton-neutron interaction L. Chen et al., PRL, 2009 p-n interactions are sensitive to the spatial overlaps Of the proton and neutron wave functions
Summary Schottky Mass Spectrometery: Time-resolved, half-live, masses Mass accuracy: 30 keV Mass resolving power: 2·106 T1/2 : > 1s Isochronous Mass Spectrometry: First large-scale measurement Mass accuracy: ≈100 keV Mass resolving power: 2 ∙105 T1/2 : ~ 50 s Masses of more than 1100 Nuclides were measured Results: ~ 350 new masses In addition more than 300 improved mass values
“Man muß etwas Neues machen, um etwas Neues zu sehen.” “You have to make something new, if you want to see something new” Next generation Georg Christoph Lichtenberg (1742-1799)
Facility for Antiproton and Ion Research SIS 100/200 SIS UNILAC FRS HESR ESR Super FRS CR NESR • Increase beam intensities: • a factor of 100-1000 for primary beam • a factor of 10 000 for secondary beam • Broad energy range: • up to 2 GeV/u • Storage & cooler rings • Increased precision, sensitivity • Reach the limits of nuclear stability • New phenomena • Nucleosynthesis paths • … Isomeric Beams, Lifetimes and Masses
References for further reading • D. Lunney, J.M. Pearson, C. Thibault, Rev. Mod. Phys. 75 (2003) 1021. • K. Blaum, Phys. Rep. 425 (2006) 1. • B. Franzke, H. Geissel, G. Münzenberg, Mass Spectrom. Rev. 27 (2008) 428.T. Radon, et al., Nucl. Phys. A 677 (2000) 75. • T. Radon, et al., Nucl. Phys. A 677 (2000) 75. • Yu.A. Litvinov, et al., Nucl. Phys. A 756 (2005) 3. • M. Hausmann, et al., Nucl. Instrum. Methods A 446 (2000) 569. • B. Sun, et al., Phys. Rev. C 78 (2008) 025806. and references therein