S π RIT-TPC experiments at RIKEN 2016 � Mizuki Kurata-Nishimura For S π RIT-TPC collaboration RIKEN, Nishina Center �
Contents v Physics Motivation v Experimental Setup v RIBF-BigRIPS beam v S π RIT-TPC v First experiment at RIKEN-RIBF-SAMURAI ( 132 Sn + 124 Sn),( 108 Sn + 112 Sn),( 124 Sn + 112 Sn),( 112 Sn + 124 Sn) ~300MeV/u v Results v Event display v Tracking v TPC-PID v Ancillary detectors v Central trigger selection v TPC performance check v Preliminary result v Summary & Perspectives Transport 2017 �
Physics motivation p We constrain symmetry energy term in EOS at Supra- saturation density. p Heavy nuclear collision with 300 MeV/u beam is expected to reach to nuclear density of two times larger than the normal nuclear density. p Symmetry energy can be studied using radioactive beams J. Phys. G: Nucl. Part. Phys. 41 (2014) 093001 Adapted fromHorowitz, et al., Xiao et al., PRL 102, 062502 (2009). Russotto et al., PLB, 697, 471 (2011) � 0 = X X = 0.5 � X = 1 � Transport 2017 �
π - / π + Production Ratio p FOPI data show π - / π + ratio is larger than (N/Z) 2 ratio. p MDI used in the IBUU04 indicates the soft EOS is preferable. p SpiRIT experiment can directly compare with common Z and different N systems. Transport 2017 �
Directed and elliptic flow � Bao-An Li Phys.Rev.Lett.85.4221(2000) � Bao-An Lee PRL85(2000)IBUU transport model � Heinz U, Snellings R. 2013 Annu. Rev. Nucl. Part. Sci. 63:123-51 � ν 1 � Transport 2017 �
BigRIPS in RIBF-RIKEN p Unstable Sn beams provided by RIBF-Big- RIPS - RIKEN. ü 132 Sn, 124 Sn, 112 Sn, 108 Sn ü ~280 MeVu p Interested beams were separated through BigRIPS and transferred to SAMURAI experimental area. Transport 2017 �
Beam & Target configurations � Purpose δ =(N-Z)/A Beam Purity Energy Periods [MeV/u] Xe 108 Sn 49% 268.9 neutron deficient δ = 0.09 Apr. 30 - May. 4 ‘16 Xe 112 Sn 44% 270.2 reference δ = 0.15 May. 4 - May. 6 ‘16 U 132 Sn 57% 268.9 neutron rich δ = 0.22 May. 25 – May. 29 ‘16 U 124 Sn 10% 270.2 reference δ = 0.15 May 30 – Jun. 1 ‘16 108 Sn (56%) � 110 Sb (1.5%) � 134 Sb 132 Sn (10%) � (49%) � Transport 2017 �
S π RIT-TPC AsAd Boards � S π RIT-TPC is designed and constructed at NSCL/ p MSU to be used in SAMURAI magnet chamber. 2D-motion target system � Transport 2017 �
Experimental Setup at SAMURAI in RIBF-RIKEN � B field 0.5T SAMURAI dipole magnet � Sn ~300MeV/u � n � 2m � NeuLAND � π + , p, d, t….. � Transport 2017 �
2D & 3D Event Display � 124 Sn + 112 Sn Top View � Side View � Transport 2017 �
Track Reconstruction p Pulse Shape Analysis f : Fixed shape � p Helix tracking: 3D momentum t 0 : time at 5% of h � ü Track separation ü Riemann fit: 2D ü Helix fit: 3D ü Clustering Cosmic event � ü Initialize GENFIT parameters p GENFIT: precise ficing (Parameterization, extrapolation) p RAVE(Reconstruction vertices) Transport 2017 �
Vertex Reconstruction � Reaction at target Before target Active target Target A. C. � Ladder � Entrance window � Background can be eliminated � Transport 2017 �
Particle Identification by TPC PID by TPC ( 132 Sn + 124 Sn @E/A=280MeV) p� π - � π + � p/Q � p π - , π + can be identified. p p, d, t, 3,4 He are also visible. Transport 2017 �
Ancillary Detectors � Active Collimator (no hit) � SBT:Start Counter (hitting) � Detector � Locatio trigger � Purpose � n � SBT: After Hitting � Count number of Start STQ beam and determine Counters � mag. � start timing � Beam Drift Chamber(BDC) � Active In front No hit � Reject beam Collimator � of the passing through target � outside of the target. � KATANA- After Pulse R eject beam-like Beam � Veto � the exit Height residues with Z window � <= greater than 20 -30mV � passing through the TPC Kyoto Left Multiplic Trigger central Multiplicity and ity >= 4 � collision events � NeuLAND : Neutron detection � Array � Right side � BDC: In beam not Reconstruct a beam Beam Drift line included � track � Chamber � after S.C. � NeuLAND � 8.5m, not Detect neutron and 30deg � included � charged light particles � Transport 2017 �
Centrality Trigger by charge of beam fragment with KATANA_V 3 paddles � Peripheral Central � p If beam like heavy fragment hits KATANA_V, veto trigger is generated. Transport 2017 �
Centrality Trigger � 30 paddles � 30 paddles � URQMD+G4 132Sn(300MeV/u) + 124Sn � Impact Parameter [fm] � Central Peripheral � Peripheral Central � Transport 2017 �
Tracking Efficiency p Tracking efficiency can be estimated from the trigger arrays, KTANA and Kyoto Multiplicity Array. p More than 80 % efficiency. Kyoto Multiplicity Array ID � Transport 2017 �
Correlation between Extrapolated track from TPC and Beam at the target. X � Each track extrapolated onto the target � Two drift chambers provide us beam position at the target � Y � Nice correlation indicates the successful operation of DAQ synchronization and vertex reconstruction Intrinsic spatial resolution is estimated to be ~ 1mm. Transport 2017 �
Flow Analysis ! ! Pz >= 400 ∑ unit P Pt b = Fragments Δ Φ Very Preliminary! � ! ! Pz < 400 ∑ unit P t = Pt Fragments p Sub-event analysis indicates an evidence of directed flow. p Azimuthal distribution of π + - , n, p, d, t, Back to back � 3 He, 4 He, w.r.t. the reaction plane can be studied. Transport 2017 �
Acceptance � Phits Simulation � θ = 80 o 70 o 60 o 50 o 40 o 30 o � Neutron coverage � thr. � Theta [deg] � 0 ~ 8 0 � pi+ � 30 ~ � MeV/c � 100 ~� proton � MeV/c � 0 ~ 55 � neutron � 1 ? ~ � MeV � 22 ~ 43 � Transport 2017 �
Summary p The first experiments were performed from April to June in 2016. p For ( 132 Sn+ 124 Sn) , ( 108 Sn+ 112 Sn) reaction, ~10M triggers accumulated. p π - 、 π + 、 p 、 d 、 t 、 He were identified. p Correlation between TPC and ancillary detectors confirmed that ü Typical space resolution is ~ 1mm ü Tracking efficiency is more than 80% p Development of tracking reconstruction code has been on progressing p The evidence of flow was observed. p Perspectives ü π + / π - ratio comparison among neutron rich and poor configurations. ü Evaluate v1 and v2 for π + , π - n, p, d, t, 3 He , 4 He. ü π + / π - , p/n ratio with respect to the reaction plane Transport 2017 �
Thank you for your aUention � Transport 2017 �
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