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NTPC Test Experiment in 2007Sep

This report provides details about the NTPC test experiment conducted in September 2007, including information about the setup, equipment used, trigger conditions, analysis techniques, and future plans.

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NTPC Test Experiment in 2007Sep

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

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

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

  6. 2 3 1 6 4 5 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

  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 1st TPC exp. • The other one is from • ring cyclotron. ) • will be replaced by 4 new ones (designed by Kon-kun)

  9. Set up

  10. Set up

  11. Set up

  12. Trigger Condition ● “Sector” trigger ・ inner ( OR of opposite 4 outers ) e.g. Sector2 trigger = (inner 2) (outer 234 5 ) 4 3 5 2 2 1 6 3 1 2 charged particle on Sector2 3 1 6 4 ・outer = upstream PMT downstream PMT 5 6 4 12 7 5 11 8 ●At least one “Sector” hit should be required. = more than one charged particle in TPC 10 9

  13. Problem & Final Trigger ● 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. solenoid TPC ●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. solenoid no signal signal Angle of Upstream PMT ●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 y y x 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 1st TPC : concentric circle layers , r-φcoordinate newTPC : 6 sectors , x-y coordinate in local sector y x r φ

  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 1st TPC experiment.)

  20. Analysis y1 ●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 y2 y y3 y4 y5 x1 x2 x3 x=p3 peakpad ADC cosmic ray data θ CR |θ|<5° 5°<|θ|<10° 10°<|θ|<15° 15°<|θ|<20° 20°<|θ|<25° 25°<|θ|<30° z pad plane

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

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

  23. VTX & VTY vtx vty

  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

  26. 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+.

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