status%20of%20experiment

1
status of experiment
TPC meeting 2004Jun04

• Another 2 scinti. has been installed to cover
  forward acceptance,
• called as forward left right.
• The vertical gap between forward up down was
  increased.
• The coverage is 6 7 layers hit. Re-alignment
  on 20th June.
• The magnetic shield for AC PMTs was moved off
  from
• tracking area. ? caused gain drop. We need to
  study the
• position dependence again. This is very time
  consuming.
• Study while beam-line tuning (not user time)
  is desirable.

trigger conditon rate_at_500kHz,CH2 (empty)
TagUpVetoACVetoTPC1SCTOF2 1 Hz
TagUpVetoACVeo(TPCSCTOF)3 42Hz (3Hz)
TagUpVetoACVeto(TPCSCTOF)2 91Hz (14.2Hz)
Pre-scale 2charge trigger by factor of 3. Totally
47Hz request 35Hz accept _at_420k tagger. The
arrival of new laser tube is delaying.
2
Beam time schedule

• In June and July, we have 102 shifts.
• We spent most of time to trigger study.
• But still AC doesnt have enough efficiency
  (98) and Imai-san is proposing to install small
  veto counter, 20mm? at AC.
• CH2, C and Cu target will be used and share of
  triggers
• by 2 1 1 .

The most important thing is to estimate of
?(1405) from real data

• As detection of ? is easer than S. We will look
  for ,
  assuming same production cross-section as ?(1405)
• Detection of ? is urgent.

From September, 2.9GeV beam will be available. We
may need to think about it.
3
re-solve RF in LEPSana
Targ
SC
TOF between target SC causes miss-ID of RF
Miss-ID of RF
4
procedure

• Solve mass of particle by TOF between SC and
  TOF.
• Select fastest particle if ntrkgt1. Get beta.
• At TrackVertex.F call findRfAgain.c
• giving beta and path-length from target and SC
  as
• arguments.
• Find RF again after correction of TOF from
  target to
• SC. And correct TOF from target to TOF-wall
• Re-calculate mass in TrackVertex.F
• New ntuple variables
• dTTarST (dTTarget2STA)
• slengSTA (path-length from SC to TOF)
• (uncorrected TOF, RF, mass will be included)

5
After RF correction
There still exist miss-ID bands. Further study
necessary.
sleng slengSTA (mm)
dTTarg2STA (nS)
TOF (nS), ntrk1
6
Runge Kutta tracking

• Uchida-san made nice frame-work for the study
• based on the analyzer of Enyo-sans ?
  experiment.
• Niiyama is improving it.
• In current version residual is calculated when a
  track cross the pad layer. Tracking get stacked
  when 2 hits found in one layer. ? Tracking based
  on arcLength
• Improve the formula to calculate residual
• Field map

Linear approximation to calcurate residual is not
good for low pt particles. circle approx.
Runge-Kutta step
measured point
pad layer
7
display runge-kutta tracking
XY
XZ
White measured Black traced point by RK
YZ
8
Residuals assuming uniform field
residual Z layer 6
residual X layer 6
residual Z layer 10
mm
mm