1. Report of the NTPC Test Experiment in 2007Sep and Others Yohei Nakatsugawa

2. NTPC test experiment in 2007Sep ●beam time: 2007Sep 20 – Oct 04 ●test experiment with almost full setup ・ NTPC ・ LEPS spectrometer ・ new LH2 target ・ new drift chamber ・ trigger scintillators ・ magnetic Field 2Tesla

3. Set up Fwd solenoid dipole TPC inner outer new DC AC target γ ※ not scaled

4. New Liquid Target System ● will be reported by Maeda-san

5. New Drift Chamber ●will be reported by Sawada-san

6. Inner Scintillators ・ 6 counters (1 for each sector) ・ one-side read out ・ fiber light guide ・ bad time resolution ~800ps  RF separation using tagger  will be reported by Yamamura-kun 1 2 3 4 5 6

7. Outer Scintillators ・ 12 counters ( 2 for each sector) ・ Both sides are read out.(  24 PMT’s) ・ time resolution = ~180ps

8. Forward Scintillators ・ temporary use ( Top & bottom ones were used for 1 st TPC exp. The other one is from ring cyclotron. )  will be replaced by 4 new ones (designed by Kon-kun)

9. Set up

12. Trigger Condition ● “Sector” trigger ・ inner ( OR of opposite 4 outers ) e.g. Sector2 trigger = (inner 2) (outer 2 3 4 5 ) 1 2 3 4 5 6 1 2 3 4 5 6 7 8 9 10 11 12 charged particle on Sector2 1 2 3 4 5 6 ●At least one “Sector” hit should be required. = more than one charged particle in TPC ・ outer = upstream PMT downstream PMT

13. Problem & Final Trigger solenoid TPC ● magnetic field of solenoid  no signal from upstream PMT’s ! (even though PMT’s were covered by iron shields)  We could not use coincidence triggers of outer scintillators. Only signal from downstream PMT’s were used as trigger signal of outer. ●tagger rate was very low ~60kcps  inner OR trigger ( (inner 1 2 3 4 5 6 ) AC ~40cps  DAQ acceptable rate  We used inner OR as main trigger. (minimum bias)

14. Angle of Upstream PMT solenoid no signal signal ●Best PMT angle was searched during no beam time in November. ●Highest signal was obtained at vertical. ●Additional light guides have been made.

15. Event Display x y y z

16. “Circle” Event ●low energy electron? ●inner OR trigger contains too many “circle” events.  hadron-like events (events with clean track) … ~10%  “Sector” trigger strongly suppress “circle” events.  hadron-like events … 80~90% “Sector” hits should be required to reduce trigger rate.

17. Analysis ●analyzer for newTPC ( NTPCana ) is under construction. ●TPCana modified for newTPC ●main difference … geometry 1 st TPC : concentric circle layers, r-φcoordinate newTPC : 6 sectors, x-y coordinate in local sector φ r x y

18. Analysis ●tracking strategy ・ find hits and determine coordinates of hit positions in local sector ・ transform from local sector to global system ・ find track candidates in global system ・ Runge-Kutta tracking in global system and calculate residual in local sector

19. Analysis ●ExB effect on drift electrons ・ ExB correction already applied to hit position ・ residual of helix fitting was improved. 310 μm  270μm ( no cut of drift length, track angle ) ・ Map of magnetic field was made with RADIA by Yamamura-kun. (Original code of RADIA was made by Ishikawa-san for 1 st TPC experiment.)

20. Analysis ●To Do ・ y coordinate determination using wire ADC ( x : center of gravity of ADC value of pad  y : center of gravity of ADC value of wire)  identification of wire pulse which corresponds to pad hit ・ dip angle dependence of pad gain Correction of ADC value of pad is needed.  dE/dx resolution y1y1 y2y2 y3y3 y4y4 y5y5 x=p 3 x3x3 x2x2 x1x1 y cosmic ray data |θ|<5° 5°<|θ|<10° 10°<|θ|<15° 15°<|θ|<20° 20°<|θ|<25° 25°<|θ|<30° z pad plane θ CR peakpad ADC

21. ~150mm CFRP cap VTZ ●vertex distribution of 2 track event ●Clear shape of LH2 target and CFRP cap can be seen.

22. VTZ of gas target ●LH2 shape disappeared CFRP remained

23. VTX & VTY vtxvty

24. dE/dx vs momentum dE/dx momentum * charge[GeV]

25. Beam Time in 2008 ● NTPC experiment 2008.Jan.25 -- Feb.25 Apr. 5 -- Apr.24 May.12 -- Aug.1

27. Physics Motivation ● Θ+ photoproduction accompanied by K* meson with deep UV laser (Eg ~ 3GeV) ● TPC can detect decay particles with large acceptance.  invariant mass of Θ+ Θ+  K0 + p ππ ● There are some theoretical calculation which suggest decay asymmetry K* from neutron target is sensitive to parity of Θ+.