A New Spectrometer in RIBF -- SAMURAI -- Ken-ichiro YONEDA RIKEN Nishina Center Carpathian Summer School 2012, June 24 – July ７, 2012

SAMURAI -- broadband spectrometer in RIBF -- Superconducting Analyzer for MUlti- particle from RAdio Isotope Beam with 7Tm of bending power RI beam from BigRIPS target superconducting coil pole(2m dia.) rotate vacuum chamber Kinematically complete measurements by detecting multiple particles in coincidence  Superconducting Magnet 3T with 2m dia. pole (designed resolution 1/700) 80cm gap (vertical)  Heavy Ion Detectors  Proton Detectors  Neutron Detectors  Large Vacuum Chamber  Rotational Stage Invariant Mass Measurement Missing Mass Measurement Proton Heavy Ion Neutron

ZeroDegree (old) RRC RILAC RIPS RARF ZeroDegree SAMURAI Here

History & Current Status of SAMURAI 1997 ? Design study started … Dec 2007 budget announcement –1.5B Yen, FY Magnet, detectors,… fabricated Oct 2010 –on-site magnet construction started Jun 2011 –designed maximum magnetic field attained Feb 2012 –Detectors, cabling, vacuum, everything done Mar 2012 commissioning May st series of experiments carried out Spokesperson Prof. T. Kobayashi (Tohoku) Co-spokesperson Prof. T. Motobayashi (RIKEN) Project Manager KY(RIKEN)

Large acceptance Large momentum byte R max / R min ~ 2 – 3 (magnet rotatable) Large angular acceptance for neutron, vertical – 5 degrees horizontal – 10 degrees (~100% coverage up to E rel ~ 3MeV, ~ 50% coverage at E rel ~ 10 MeV)

Photos ~magnet construction~ Rails for rotatable base Rotatable base with the first layer Magnet yoke with poles Coils with cryostats, LHe vessels Vacuum chamber COMPLETED MAR 2011

SAMURAI Current View

Various Configuration ( , n) reaction: neutron-rich side( , p) reaction: proton-rich side (p,p’), (p,2p), (p,pn), … pol. d-induced reactionEOS measurement Various usage  Variety of physics subjects covered with SAMURAI SAMURAI allows versatile usage

Invariant Mass Spectroscopy Invariant Mass M A Target b Incident beam A A* a a+b A  a+b  Excitation Energy

Coulomb Breakup – 1n Case Non energy-weighted sum rule 1234 Excitation Energy (MeV) dB(E1)/dEx(e 2 fm 2 /MeV) T. Nakamura et al., PLB 331,296 (1994) N. Fukuda et al., PRC 70, (2004) Huge Strength appears at low Ex (usually <10 -3 )  signature of halo structure H. Esbensen et al.,NPA 542,310 (1992)

Coulomb Breakup – 2n Case T. Nakamura et al., PRL 96, (2006) B(E1) = 1.42±0.18 e 2 fm 2 11 Li+Pb Extraporated B(E1 ) 1.78(22) e 2 fm 2  = deg -18 NOT 90 deg !!

( , n) reaction: neutron-rich side Detector System  ( , n) measurement mode NEBULA Detectors for Heavy Ion Position measurement Drift Chambers Beam / Fragments Charge measurement Ion Chambers Beam / Fragments Velocity measurement Plastic hodoscope Cherenkov counter Total E measurement Pure CsI detector NEBULA Plastic scintillator 240 modules Effective Area : 3.6 m (H) × 1.8 m (V) ~ 100 % E rel < 3 MeV ~ 40 % E rel ~ 10 MeV Efficiency ~ 66 % (Half: ~40 %) Half volume is ready in summer All detectors are ready in Pb target

Commissioning in March 2012 Start all detectors, DAQs, with beam Beam transport to SAMURAI Heavy ion detectors optimization NEBULA calibration –Time-zero with high-energy gamma –Efficiency measurement (inc. 2n cross talk) with 7Li(p,n) reaction Brho scan HI-neutron coincidence measurement –17C  16C+n 15B+n –15C  14C+n –14Be  12Be+2n Everything worked fine !!

Resolution check Goal resolution  R /R achieved Plots by Dr Isobe Brho 3T

Day-One Experiments “Spectroscopy of unbound oxygen isotopes” –Spokesperson: Yosuke Kondo (Tokyo Tech) –Observation of unbound oxygen isotopes “Exclusive Coulomb Breakup of neutron drip-line Nuclei” –Spokesperson: Takashi Nakamura (Tokyo Tech) –Coulomb breakup of neutron-rich boron and carbon isotopes “Structure of 18,19 B and 21,22 C” –Spokesperson: Nigel Orr/Julien Gibelin (LPC-Caen) –Observation of unbound states in neutron-rich boron and carbon isotopes May 5 – 28, 2012, successfully done Now data analysis ongoing

Various Configuration ( , n) reaction: neutron-rich side( , p) reaction: proton-rich side (p,p’), (p,2p), (p,pn), … pol. d-induced reactionEOS measurement SAMURAI allows versatile usage READY !! Commissioned in March ’12 DAY-ONE exps in May ‘12 Various usage  Variety of physics subjects covered with SAMURAI

Nucleosynthesis in p-rich region: rp-process Very hot, dense environment such as nova,  -ray burst Hydrogen burning proton capture proton capture  decay  decay sequentially to produce sequentially to produce heavier elements heavier elements Important to understand natural abundance （ esp. p-nuclei ） cosmic  -rays from ongoing nucleosynthesis ongoing nucleosynthesis Energy production in stars ….. Need proton capture cross section of unstable nuclei Ne nova M.Wiescher et.al. Phil. Trans. R. Soc. Lond. (1998) {

γ 23 Al High-Z target (Pb) 22 Mg p 23 Al * Incident beam 22 Mg(p,  ) 23 Al 23 Al( ,p) 22 Mg 26 Si(p,  ) 27 P 27 P( ,p) 26 Si  ~ 60nb  ~ 4mb  ~ 60nb  ~ 4mb 23 Al 22 Mg + p Inverse reaction Cross section far larger Detailed valance + virtual photons Coulomb Breakup – 1p Case -- Inverse of (p,  ) reaction --

Resonant capture strength  Resonant capture strength  2j+1 (2j 1 +1)(2j 2 +1) pp +p+p 23 Al 22 Mg + p ~   when  p pp  Determination of  is important In Coulomb dissociation, measured excitation cross section  B(E2)   Resonant Capture -- Importance of   --  =

Relative energy [keV] Counts /150keV ・ energy resolution 170 keV (E rel = 400 keV) ・ identify reaction through the first excited state clearly. continuum component: E1, constant astrophysical S -factor 1 st excited state (objective state) Higher excited state

Cosmic γ-emitter Ne nova M.Wiescher et.al. Phil. Trans. R. Soc. Lond. (1998) T [GK] ρ [g/cm 3 ] β decay is favored Which ? Nucleosynthesis in explosive hydrogen burning (Novae, X-ray bursts) Nova Model M1 : J.Jose et al Astrophys. J (1999) M2 : C. Iliadis et.al. Astrophys. J. Supp (2002)

Coulomb Breakup in heavy region candidates of waiting point, bottle neck candidates of waiting point, bottle neck understand origin of p-nuclei, natural abundance understand origin of p-nuclei, natural abundanceRequirements ・ Heavy elements production RIPS  RIBF + BigRIPS RIPS  RIBF + BigRIPS ・ Improvement exp. resolution Silicon Telescope Silicon Telescope  SAMURAI spectrometer  SAMURAI spectrometer resolution ~ 1/700 resolution ~ 1/700 up to 100 Sn up to 100 Sn Thielemann et al., Prog. Part. Nucl. Phys. 46 (2001) 5. Coulomb Breakup in Ni - Sn region

Detectors for Proton Proton Drift Chamber Plastic Hodoscope Silicon Strip Detector Broad dynamic range Both proton & heavy ion (Z < 50) hit the detector Capability of high density signal processing Signals of about 2500ch in total Modify integrated ASD circuit HINP16C in collaboration with Texas A&M, Washington Univ, Louisiana (TWL) collaboration HINP16C ch processing in 1 chip two output for energy and timing Detector System  ( , p) measurement mode Detectors for Proton ( , p) reaction: proton-rich side All detectors are ready in Detectors for Heavy Ion Silicon Strip Detector Pb target To be ready in 2013.

Various Configuration ( , n) reaction: neutron-rich side( , p) reaction: proton-rich side (p,p’), (p,2p), (p,pn), … pol. d-induced reactionEOS measurement SAMURAI allows versatile usage READY !! Commissioned in March ’12 DAY-ONE exps in May ‘12 TO BE READY in 2013 US-RIKEN collaboration Various usage  Variety of physics subjects covered with SAMURAI

Nuclear EOS Study by using TPC Symmetry energy Symmetry energy Asymmetric system High density (e.g.  ~2  0 )   1: neutron star } measurement required

Au+ Au ? MSU RIBF GSI Isospin diffusion, n-p flow Pion production RIBF can constrain the symmetry energy at ~ 2  0. Requires data with controlled variations in system asymmetry RIBF can constrain the symmetry energy at ~ 2  0. Requires data with controlled variations in system asymmetry Xiao, et al., arXiv: (2008) Reisdorf, et al., NPA 781 (2007) 459.

 Asymmetric system  124 Sn+ 132 Sn(   ~2  0 )  TPC+NEBULA  JPN+US collaboration  Ready in 2014

Rigid Top Plate Primary structural member, reinforced with ribs. Holds pad plane and wire planes. Front End Electronics Liquid Cooled Pad Plane (108x112) Used to measure particle ionization tracks Field Cage Defines uniform electric field. Contains detector gas. Thin-Walled Enclosure Protects internal components, seals insulation gas volume, and acts as major structural member Voltage Step-Down Prevent sparking from cathode (20kV) to ground Target Mechanism Calibration Laser Optics beam SAMURAI TPC: Exploded View Rails Inserting TPC into SAMURAI vacuum chamber

Proposed research program Typical rates at 10 4 /s are 3-4 pions/s of each charge and about 5 n’s/s  Goal is to run up to 10 5 /s Ideal would be to run 3-4 weeks/year. This corresponds to two experiments that each measure two pairs of systems: e.g. 132 Sn+ 124 Sn, 105 Sn+ 112 Sn at one incident energy. ProbeDevicesE lab /A (MeV) Part./sMain Foci Possible Reactions FY  +  -,p, n,t, 3 He TPC Nebula E sym m n *, m p * 132 Sn+ 124 Sn, 105 Sn+ 112 Sn, 52 Ca+ 48 Ca, 36 Ca+ 40 Ca 124 Sn+ 124 Sn, 112 Sn+ 112 Sn 2014  +  - p, n,t, 3 He TPC Nebula  nn,  pp  np 100 Zr+ 40 Ca, 100 Ag+ 40 Ca, 107 Sn+ 40 Ca, 127 Sn+ 40 Ca Slide by T. Murakami

Various Configuration ( , n) reaction: neutron-rich side( , p) reaction: proton-rich side (p,p’), (p,2p), (p,pn), … pol. d-induced reactionEOS measurement SAMURAI allows versatile usage READY !! Commissioned in March ’12 DAY-ONE exps in May ‘12 TO BE READY in 2013 US-RIKEN collaboration TO BE READY in 2014 SAMURAI-TPC collaboration (US-KYOTO-RIKEN) Various usage  Variety of physics subjects covered with SAMURAI

Various Configuration ( , n) reaction: neutron-rich side( , p) reaction: proton-rich side (p,p’), (p,2p), (p,pn), … pol. d-induced reactionEOS measurement SAMURAI allows versatile usage READY !! Commissioned in March ’12 DAY-ONE exps in May ‘12 TO BE READY in 2013 US-RIKEN collaboration TO BE READY in 2014 Tohoku-RIKEN TO BE READY in 2014 SAMURAI-TPC collaboration (US-KYOTO-RIKEN) Various usage  Variety of physics subjects covered with SAMURAI

Various Configuration ( , n) reaction: neutron-rich side( , p) reaction: proton-rich side (p,p’), (p,2p), (p,pn), … pol. d-induced reactionEOS measurement SAMURAI allows versatile usage READY !! Commissioned in March ’12 DAY-ONE exps in May ‘12 TO BE READY in 2013 US-RIKEN collaboration TO BE READY in 2014 Tohoku-RIKEN Exps approved Beaumel (Orsay) Sakaguchi (Kyushu) Sasano (RIKEN) New Detector MINOS (Saclay) to be ready in 2014 TO BE READY in 2014 SAMURAI-TPC collaboration (US-KYOTO-RIKEN) Various usage  Variety of physics subjects covered with SAMURAI

Construction Members Construction Team Member (*Leader) Magnet and Infrastructure: Vacuum system and Utilities: Heavy ion detectors: Y. Matsuda (Kyoto), K. Sekiguchi, N. Chiga, graduate students, T. Kobayashi* (Tohoku), H. Otsu (RIKEN) Neutron detectors (NEBULA): R. Tanaka (Tokyo Tech), Y. Satou (Seoul National Univ.) Proton detectors: K. Yoneda*, Y. Togano, M. Kurokawa, A. Taketani, H. Murakami, T. Motobayashi (RIKEN), K. Kurita (Rikkyo), T. Kobayashi (Tohoku), L. Trache (Texas A&M) and the TWL collaboration Polarized deuteron induced reaction experiment devices: K. Sekiguchi*, T. Kobayashi, Y. Matsuda, graduate students (Tohoku) Time projection chamber: H. Sakurai (RIKEN), W.G. Lynch (Michigan State) and SAMURAI TPC collaboration In-House Work Force: Research Instruments Group (T. Kubo - Group Leader) SAMURAI Team (T. Motobayashi*, H. Sato, Y. Shimizu, K. Yoneda) T. Kobayashi (Tohoku) ・ Spokesperson T. Motobayashi (RIKEN) ・ Co-spokesperson K. Yoneda (RIKEN) ・ Project manager H. Sato*, K. Kusaka, J. Ohnishi, H. Okuno, T. Kubo (RIKEN) H. Otsu*, Y. Shimizu (RIKEN) T. Nakamura*, Y. Kondo, Y. Kawada, T. Sako, T. Murakami* (Kyoto), T. Isobe, A. Taketani, S. Nishimura, Y. Nakai,

Summary SAMURAI started working –Commissioning in March 2012 –Day-One experiments in May 2012 –All done successfully Extension of SAMURAI collaboration –Construction base  Physics outcome We welcome your participation in SAMURAI collaboration !!

Thank you for your attention !