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Next-stage experiments with new LEPS standard setup

Next-stage experiments with new LEPS standard setup. Physics motivation. new TPC (NTPC) 2.97 GeV g New LH 2 ,LD 2 target. Decay asymmetry of K*  sensitive to the parity of exchange particle(s). information of both missing masses and invariant masses.

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Next-stage experiments with new LEPS standard setup

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  1. Next-stage experiments withnew LEPS standard setup Physics motivation new TPC (NTPC) 2.97 GeV g New LH2,LD2 target Decay asymmetry of K*  sensitive to the parity of exchange particle(s) information of both missing masses and invariant masses

  2. Final Design of New TPC (2005 Jan.) 750 560 900 Pad size: 5.1mm x 14.5 mm (gap : 0.5 mm) Pad row : parallel to anode wires, 9 layers 3 anode wires with 5mm spacing are on one pad layer. Inefficient region : 10 % of the whole region TPC construction was completed in early 2006 and it was tested.

  3. Add some new counters(based on the experience of 1st TPC exp.) • To improve trigger condition  inner scintillators Select events from target Cut BG events from upstream • To improve particle identification  reconstruct outer scintillators with both-side readout TOF information for PI • To improve the momentum resolution for forward going particles  thin drift chamber with 60cmf effective area New DC is also used in place of SSD for the forward spectrometer. • To put the TPC& DC close to the dipole  modifythe forward scintillators

  4. Particle Identification de/dx vs Momentum and/or TOF vs Momentum (PI is difficult for higher momentum due to small inner diameter of the solenoid !) pK 2s separation at 0.5 GeV/c  s(TOF)= 150ps or s(de/dx)/(dedx)=16% L=25 cm Ar, 1 atm 300 ps 1.22 keV

  5. LH2 target New DC Outer scinti. TPC Inner scinti. Illustrated by J.Y.Chen Solenoid

  6. One thing I know it should be changed, but it still not be improved.  Time constant (CR) of the PreAmp 4pF×33kW =132 ns

  7. wire plane Charged particle b Q On the dip angle dependence of the TPC pulse height total charge Q ∝ b/cosQ time difference of charge collection Dt = b tanQ/ v (b~15mm (pad), ~5mm(anode) v~5cm/msec ) Charge sensitive PreAmp. Simple model for the input charge T0: charge collection time i0=Q/T0 (t<T0) Vout is analytically solved

  8. for pad, Q=30° T0=173 ns Q=45° T0=300 ns Q=60° T0=520 ns dip-angle dependence of the pulse height and peak time should be corrected in the offline analysis !!

  9. From the end of next January, new experiments will start. Please come and join us. Enjoy physics from new data !

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