S. Purushothaman for the FRS Ion Catcher Collaboration  A novel method for precision experiments with thermalized short lived nuclides produced at relativistic energies S. Purushothaman for the FRS Ion Catcher Collaboration EuNPC 2015 Groningen, August 30 – Septemebr 4, 2015

Experiments with Exotic Nuclei Exotic nuclei far away from the valley of stability are coming in reachable distance for existing and future facilities Challenges are: Low production rates Short half-lifes Fast separation and identification N Z rp-process, Novae and x-ray Bursts r-Process and supernovae Halo, Skin Nuclei New Decay Modes, e.g. 2 p-Emission Superheavy Elements s-process C.E. Rolfs, W.S. Rodney, Cauldrons in the Cosmos, 1988 nuclear models can describe the binding energies (or masses) of nuclei, which are stable or in the vicinity of the line of beta-stability (the so-called ’valley of stability’) quite well and in agreement with each other and in particular with measured masses. They predict very different values for nuclei, whose masses are not yet known experimentally. The situation is similar with decay properties, shapes, and other properties of exotic nuclei, r- and p-process nucleo-synthesis pathways employ exotic nuclei far off stability. Therefore measurements of the binding energy and the decay properties of exotic nuclei have important applications in nuclear astrophysics. Moreover, they help to understand the structure of the nuclei. For instance, they provide important input for nuclear structure theories and various mass models and they allow tests of the shell structure and the evolution of shell effects far from stability. Solar Abundance Structure & Dynamics of Exotic Nuclei Nuclear Astrophysics

NUSTAR@FAIR Nuclear Structure, Astrophysics and Reactions GSI FAIR SIS18 UNILAC SIS100/SIS300 Super-FSR HESR RESR/ CR NESR CBM PANDA Rare Isotope Production Target Nuclear Structure, Astrophysics and Reactions Low Energy Branch (LEB) @ SuperFRS Super-FRS  increased intensities Higher energies shorter lifetimes Access to more exotic nuclei  especially 3rd r-process peak is irradiated by an intense proton beam, introducing nuclear reactions in the tar- get. The ISOL method features high production yields even for very exotic nuclei far from stability, and is thus ideally suited for nuclear astrophysics and nuclear structure studies far from stability. Its main disadvantage is that the exotic nuclei need to diffuse out of the bulk of the target for ionization and transportation as a low energy beam, therefore the production is subject to restrictions by chemistry, e.g. refractory elements are hard to produce. Quelle: I. Peter 3

NUSTAR@FAIR: Low Energy Branch (LEB) Experiments ~ eV - keV Production 100...1500 MeV/u The three main nuclear reactions are fusion, projectile fragmentation and fission. MATS (Precision Measurements of very short-lived nuclei using an Advanced Trapping System for highly charged ions) masses decay properties LaSpec (LAser SPECtroscopy) Isotope shift, hyperfine structure charge radii and nuclear moments Eur. Phys. J. Special Topics 183 (2010) 1

Low Energy Experiments at In-flight Facilities 100...1500 MeV/u ~ MeV/u ~ eV ~ keV Fragment Separator Stopping Cell MR-TOF MS Experiments (Trap, Laser,..) Target Primary Beam In-flight Production In-flight Separation Stopping / Thermalization Isobar Separation SuperFRS MATS / LaSpec FAIR Fusion FRIB RIKEN

Efficient stopping: Range & range straggling ΔxΔp=0 > 0 Absorption probability 0.5 1.0 number-distance curve straggling absorber thickness mean range Δx = 0, Δp = 0 mean range = Range straggling ΔxΔp≠0 > ΔxΔp=0 Absorption probability 0.5 1.0 straggling absorber thickness mean range number-distance curve Δx = 0, Δp = 0 Δx = 0, Δp ≠ 0 mean range =

Low Energy Experiments at In-flight Facilities 100...1500 MeV/u ~ MeV/u ~ eV ~ keV Fragment Separator Buncher / Degrader Stopping Cell MR-TOF MS Experiments (Trap, Laser,..) Target Primary Beam In-flight Production In-flight Separation Momentum Compression Stopping / Thermalization Isobar Separation SuperFRS MATS / LaSpec (σR) σR σR0 Absorption probability 0.5 1.0 number-distance curve straggling absorber thickness mean range J.S. Winfield et al., NIM A 704 (2013) 76

Cryogenic stopping cell FRS ion catcher setup (a test bench for LEB at FAIR) MRTOF-MS Diagnostic unit Cryogenic stopping cell Cooling system W.R. Plaß, et al., NIMB 317 (2013) 457-462

High-density Operation Cryogenic Stopping Cell (CSC) Extraction RFQ DC cage electrodes 100 cm Inner chamber (cooling by cryo-cooler ~ 60-70 K) Outer chamber (room temperature) Exit hole RF Carpet CSC Areal density Online Operation: ~6 .3mg/cm2 2 times compared to stopping cells using an RF structure PCB-based RF carpet Small spacing & Easy cunstruction  high RF repelling field High-density Operation Developed in Collaboration A. Tolmachev, Int. J. Mass Spectrom. 203 (2000) 31 M. Wada et al., NIM B 204 (2003) 570 M. Ranjan et al., Europhys. Lett. 96 (2011) 52001

Efficiency of the CSC Bρ-ΔE-Bρ CSC Si detector High areal density of 6.3 mg / cm² results in a stopping efficiency of ~ 20-30 % for relativistic projectile fragments with 1GeV/u Ion survival and extraction efficiency e. g. for 223Th: 80 - 100 %) Total efficiency up to 30% time after ion bunch enters CSC [ms] T1/2(221Ac) = 52 ms decays extraction and decay mean extraction time decay only Bρ-ΔE-Bρ Z A/Q 223Th CSC Si detector Purushothaman S. et al, EPL 104 (2013) 42001

Universal mass spectrometer and mass separator Multiple-Reflection Time-of-Flight Mass Spectrometer Universal mass spectrometer and mass separator (works for all elements, stable and unstable ions) Mass Resolving Power Mass Measurement Accuracy Measurement Duration Ions required for mass measurement up to 600,000 down to 10-7 2…20 ms ~ 10 ions MR-TOF-MS W.R. Plaß et al., Int. J. Mass Spectrom. 394 (2013) 134 T. Dickel et al., NIM A 777 (2015) 172 - 188 M. I. Yavor et al., IJMS 381382,(2015)1

Measurement and Separation of Isomers First measurement of isomer-to-ground state ratio Measurement of excitation energy: (1472  120) keV Lit.: (1462  5) keV Measured ratio: (2.5  0.8) m/m = 250,000 TOF = 8.7 ms 1472 keV 211Po Measurement using the TOF detector T. Dickel et al., Phys. Lett. B 744 (2015) 137

Measurement and Separation of Isomers First spatial separation of ground state and isomeric state in a MR-TOF-MS Proof-of-principle: production of isomerically clean beams by MR-TOF-MS 211Po Separation using the Bradbury-Nielsen gate, measurement using the Si detector T. Dickel et al., Phys. Lett. B 744 (2015) 137

Perspectives: Isomer Measurement with MR-TOF-MS Isomers given in the Atomic Mass Evaluation 2012 Gamma-ray coincidence spectroscopy Mass spectrometry (SMS, Penning traps) Measurement of isomers and production of isomeric beams with MR-TOF-MS Efficient (broadband), universal (all nuclides) search and measurement of isomers (excitation energy, isomeric ratios) Isomerically clean beams (decay spectroscopy, reactions)

Results: Mass Measurement Accuracy First results (here: same-turn number, non-overlapping peaks) Preliminary T1/2 = 19.5 ms T1/2 = 32.3 ms T1/2 = 35.0 ms T1/2 = 23.9 min Mean deviation from literature: -0.05 ppm = -6 keV @ 133I Mean uncertainty: 0.5 ppm = 60 keV @ 133I Residual systematic uncertainty: 0.15 ppm = 20 keV @ 133I ~ 130 counts = systematic uncertainty of 0.15 ppm @ 250000 resolving power Preliminary

Summary & Outlook Summary Cryogenic Stopping Cell Total efficiency up to 30% Mean extraction time ~24 ms Multiple-Reflection Time-of-Flight Mass Spectrometer Mass measurement of short-lived nuclides with mass accuracy of 0.5 ppm Isotopes with half-lifes of only ~20 ms measured First spatial separation of ground state and isomeric state in a MR-TOF-MS Outlook Conceptual design of the final cryogenic stopping cell for the LEB x5 higher areal density x5 faster extraction Higher intensity capabilities ~107 U/s Mean

Acknowledgements FRS Ion Catcher Collaboration Funding: F. Amjad2, S. Ayet2, T. Dickel1,2, P. Dendooven3, M. Diwisch1, J. Ebert1, A. Estrade2, F. Farinon2, H. Geissel1,2, F. Greiner1, E. Haettner1, C. Jesch1, N. Kalantar-Nayestanaki3, R. Knoebel2, J. Kurcewicz2, J. Lang1, I. Moore4, C. Nociforo2, M. Petrick1, M. Pfuetzner2, W.R. Plaß1,2, S. Pietri2, A. Prochazka2, S. Purushothaman2, M. Ranjan3, M.P. Reiter1, A.-K. Rink1, S. Rinta-Antila4, C. Scheidenberger2, M. Takechi2, Y. Tanaka2, H. Weick2, J.S. Winfield2, M.I. Yavor5 1 II. Physikalisches Institut, Justus-Liebig-Universität Gießen, Gießen, Germany 2 GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany 3 KVI, University of Groningen, The Netherlands 4 University of Jyväskylä, Jyväskylä, Finland 5 Institute for Analytical Instrumentation, RAS, St. Petersburg, Russia Funding: Univ. Groningen and GSI, HGF and GSI (VH-NG 33), GSI F&E (GIMET2) BMBF (06GI185I, 06GI9114I, 05P12RGFN8) State of Hesse (LOEWE Center HIC for FAIR) JLU and GSI (JLU-GSI strategic Helmholtz partnership agreement)

Production of exotic nuclei by ISOL and In-flight

FRS ion catcher setup (a test bench for LEB at FAIR) SuperFRS LEB MATS / LaSpec In-flight Production Separation Momentum Compression Stopping / Thermalization Target Fragment Separator Buncher / Degrader Stopping Cell Experiments (Trap, Laser,..) Primary Beam 100...1500 MeV/u ~ eV ~ MeV/u Dispersive Stage Monoenergetic Ion Beam p+p p-p p p’ Degrader with Different Momenta p+p, p, p-p H. Weick et al., NIM B 164 (2000) 168

Rate capability 221Ac and 213Fr Challenge of stopping high energy, high mass beams (1GeV/u, projectile fragments) deposit ~270MeV in stopping gas (3MeV/u) corresponding to 5106 He/e- pairs per ion Study of the rate capability of the CSC 221Ac and 213Fr projectile fragments 104 ions/s with full efficiency (~1010 He/e- pairs) Preliminary

FRS Ion Catcher: Measured Nuclides Commissioning experiments in 2011, 2012, 2014 Thermalization of 15 projectile fragments 6 fission fragments 238U Projectile Fragmentation Nucleon-nucleon collision, abrasion, ablation 238U Projectile Fission Electromagnetic excitation, fission in flight

MR-TOF-MS as Mass Tagger Scaling of the FRS PID over large range requires recalibration (need to identify one isotope in the ID plot) MR-TOF-MS as mass tagger Correct identifcation of 134I Universal and fast technique (~20 min) Z calibration off by Z = 3.5

Mass Measurement: Uranium Fission Fragments Mass measurement of 238U fission products produced at 1000 MeV/u Mass resolving power (FWHM) ~ 360,000 Identification of low-lying isomers Preliminary 1.6 MeV m/m = 360,000 0.3 MeV

Mass Measurement: Uranium projectile Fragments 218Rn + Half-life: 32 ms 93 ions 213Rn+ Half-life: 19.5 ms 176 ions Preliminary 220Ra 2+ Half-life: 17.9 ms 11 ions Mass resolving power ~ 175,000 Mass measurements performed at an ion rates as low as 5 detected ions/hour

Experiments at the LEB MATS (Precision Measurements of very short-lived nuclei using an Advanced Trapping System for highly charged ions) address 3rd r-process peak at N=126 shell closure world wide unique research possibility r-Process and Supernovae rp-Process, Novae and X-ray Bursts Nuclear Astrophysics

Concept of the future CSC x5 higher areal density x5 faster extraction Higher intensity capabilities Nozzle 0.01 mbar 300K 100mbar 70K ~1m 0.01 mbar 300K Extraction region RF Carpets 10mbar 70K ~0.1m Mono-energetic High-energy ion beam ~0.2m Stopping region 300mbar 70K ~2m T. Dickel et al., GSI Report 2013