TOF for New-TPC experiment 1.Time-of-Flight 2.Missing mass of single-K +, proton 3.New-DC Mizuki Sumihama May, 2 nd, 2008

Setup of forward [mm] ~ 1 m TPC New-DC DC1 DC2 DC3 TOF FWD(Plastic) Dipole Momentum: No SVTX(SSD), New-DC TOF : rf-TOF-wall, (Distance between target and fwd is ~1m.)

Tagger-Plastic counters for 2 nsec structure of RF signals Standard setup : We use Start counter to solve 2 ns ambiguity of RF signals. But New-TPC exp. : Distance between TGT and FWD is about 1m (too long!), and TOF between TGT and FWD is not negligible and difficult to solve the 2 ns ambiguity.  Use tagger plastic counters

2 nsec structure in Tagger 2 ns ambiguity can be solved by Tagger plastic counters After time-work correctionBefore time-work correction

Mass spectra Few events not to solve 2ns-ambiguity.

Missing mass spectra MM(K+) MM(p) E  < 2 GeV E  < 2.4 GeV All n(  +)    E  function up to 3GeV temporary determined by Kato Require a hit in outers  No signal of     ~5 days

Plots from the data with standard setup –Not any request at side region MM(K+) MM(p) n     <25 degree

Z-vertex Target position Vertex resolution for 2 track events is not good because of No SVTX(SSD) and small opening angles.  improvement including New-DC ??  < 14 degree Polar angle for single track

TOF with Tag-PL and Outers Front view of TDC, Inner and Outer One-side readout for Inner counters, time resolution is about 800 ps by Yamamura. Start timing is determined by RF signals and solve 2 ns ambiguity by Tagger-PL. Stop timing is determined by Outers. Time resolution is about 200 ps by Yamamura.

 vs. momentum,dE/dx Information of path length, momentum and dEdx by Nakatsugawa-kun.

New-DC Pitch 14 mm YY’UU’VV’ 6 planes U/V angle 30 degree the same as DC2 and DC3 Accept events go through forward. Help to determine momentum vector and vertex points in mixed magnetic field of Dipole and Solenoid. TPC New-DC Installation of NDC in program for side tracking (TPCana) is by Uchida. Forward LEPS

Magnetic field ~0.1T ~0.05T New-DC

97mm sense wire (Au-W) φ30μm #50×6 Layer potential wire (Au-BeCu) φ100μm #50×6 Layer 7mm Cathode sheet (aluminized mylar) 12.5μm V V’ U U’ Y Y’ New DC  DC0

xt-curve Trace back from DC1 to each planes of NDC and determine initial xt-curve. iteration to have better xt curve. Solve left-right ambiguity By positions of fired wires In Y/Y’, U/U’ and V/V’. Require 6 hits in NDC. Y Y’ U U’ V V’ Expected hit position - Wire position

outlook Egamma calibration up to 3 GeV Alignment of New-DC Require hits in all 6 planes  relax to 5 or 4 hits. The number of clusters in NDC is sometime huge.  need a cut condition by an efficient /safety way Check run dependence of t0/xt-curve ………………..