1 KEK Beam Test Analysis Hideyuki Sakamoto 15 th MICE Collaboration Meeting 10 st June,2006

2 Contents Setup of KEK beam test Alignment correction Light yield Tracking within B-Field Summary

3 KEK Beam Test KEK beam test was performed on September 30th to October 7th in 2006 at KEK-PS  2 beam line with the collaboration of UK, US, Europe and Japan. Main purpose is to confirm the performance of SciFi tracker in 1-Tesla solenoid field. Prototype SciFi tracker –SciFi tracker is consists of 4 stations, and there are 3 views for station B,D and 2 views for station A,C. VLPCs –Photon signals from Scintillating fiber were readout by VLPCs. –We used two VLPC cassettes. One of them has high gain and the other has low gain. –VLPCs were cooled down to 9K by a cryocooler. Schematic view of detectors located in the beam line Prototype SciFi Tracker with 4 Stations

4 Setup TOF hodoscope JACEE MAGNET (B=1T) Readout System Cryocooler AFE Board Low Gain Cassette High Gain Cassette Before installing waveguides BEAM  2 Beam Line

5 Analysis Scheme This analysis aims to estimate light yield and efficiency. First, fiber hits are defined on each view. Then, tracks are reconstructed in the 3 stations other than the test station, and are extrapolated to the test station. Finally, the residual between extrapolated track and the hits on the test station is calculated. Residual distribution is also calculated by Monte Carlo to be compared with data. Hit definition –A fiber channel of which measured pulse height is above 2.5 photo-electron is defined as a hit. Most of VLPC noise are rejected by this cut. Tracking –Track is reconstructed by 2D tracking using 3 stations other than the test station. Hits on the test station are not included in the tracking. To select good tracks, chi-squared of the reconstructed track is required to be less than 1. 2D tracking is performed at each Views individually. BEAM 3 GeV/c  DCAB

6 Event Selection To ensure that a pion surely passes through SciFi tracker, PID by TOF of D1 and D2 counter are required. Integration window in Trip chip is measured. Time difference from the beam trigger is restricted to reject events in which beam particles are not synchronized to Trip gate. STATION B STATION A STATION D STATION C D1TOFD2SciFi

7 Alignment Correction This study is based on latest mapping table, Version12. Alignment correction as well as mapping error is checked by finding difference of hit fibers with fibers which is extrapolated by fitting.

8 Alignment Correction View V View X View W Station B Fiber #Residual

9 Alignment Correction View V View X Station A Fiber #Residual

10 Alignment Correction View X View W Station C Fiber #Residual

11 Alignment Correction View V View X View W Station D Fiber #Residual

12 Searching for center fiber In order to find combination of crossing of fibers of 3 views, adjustment is done by shifting X-view by same amount. –Down figure shows the results after shifting by -20 fibers. W view X view V view #101 #81

13 Pitches for Station D In design, all 3 Views in new 4 th Station D has 427  m pitches. But DATA shows it is 420  m as other Views. Difference of fiber# Fiber# V View X View W View Red = 427  m Black = 420  m

14 Light Yield –X view 7.9 ±0.1 p.e.10.3± 0.2 p.e. 8.8±0.2 p.e.4.7±0.1 p.e. 14.5± 0.4 p.e ±0.9 p.e. 8.5 ±0.6 p.e.

15 Light Yield –V view 8.6±0.1 p.e.9.1±0.1 p.e. 4.7±0.2 p.e. 15.6±0.4 p.e. 15.3±0.4 p.e. 9.1±0.5 p.e.

16 Light Yield –W view 9.8 ±0.2 p.e. 9.0±0.1 p.e. 5.1±0.2 p.e ±0.4 p.e. 9.4±0.5 p.e.

17 Light Yield Summary StationView Gain of cassette 3HF concent. Light Light N Ratio BXLOW BVLOW BWLOW AXLOW AVLOW CXHIGHmixture CWHIGH DXHIGH DVHIGH DWHIGH

18 Analysis Scheme Tracking reconstruction is held by MC in order to compare with DATA. –250 MeV/c muon beam is used for this analysis. –Initial beam of 4cm x 4cm squared distribution with Pt=0 are used for MC simulation and beam profile at TOF hodoscope is compared. Reconstructed Pt,Pz distribution and chi2 distribution are compared with MC. BEAM 250MeV/c  DCAB 1 Tesla TOF T1 4cmx4cm

19 Beam Profile –MC and DATA DATAMC Horizontal Width (cm)10.0 Vertical Width (cm)10.0

20 Pt, Pz Distribution – MC viewDCAB Pt (MeV/c)28.5 (8.6)29.0 (9.7)29.4 (10.3)29.4 (10.0) Pz (Mev/c)227.2 (2.3)226.8 (2.4)226.4 (2.4)225.9 (2.4) Station B PT distribution MeV/c Station C Station A Station D PZ distribution Station B Station C Station A Station D

21 Pt,Pz Distribution – DATA Muon electron muon pion PT distribution PZ distribution PT distribution PZ distribution MeV/c Reconstructed mom.Muon Pt (MeV/c)28.3 (10.3) Pz (Mev/c)230.7 (26.7)

22 Reconstructed Distri. – MC Reconstructed mom.Muon Pt (MeV/c)30.1 (10.3) Pz (Mev/c)233.7 (19.7)

23 Chi2 Distribution –MC and DATA Chi2 is defined by residue of hit position and reconstructed track divided by sigma, 1mm. Peaks around 1 is the same as MC. But width is little more broad than MC. It should be checked. MeanRMS DATA MC DATAMC

24 Summary Alignment corrections are done using latest mapping table, Version12. Light yield for all views of all stations are studied by 3D tracking. –There is no big difference with 3 kinds of 3HF concentration (except for StationD). Tracking with B-Field are studied. –Reconstructed Pt, Pz distribution looks like same with MC and DATA. –Chi2 distribution of MC also looks like same as DATA, which confirms that DATA is reconstructed as expected. –Next step is estimating momentum resolution by MC.

25 Backup

26 Light Yield Light yield is estimated by fitting the peak with gaussian. Measured light yield is similar to the result of cosmic-ray test. Station BACD 3HF Concentration (ppm) 5000 mixture2500 Gain of cassette Low High Measured light yield (p.e.) Data from Cosmic-ray test n/a This peak is caused by ADC saturation.

27 Residual Distribution Station BACD Sigma DATA / / / / Sigma MC / / / / DATAMC

28 Efficiency Efficiency is determined by N1/ N2; –N1= Number of events which contains fiber hits within the road width determined at each station –N2=Number of events with L1A cut & TOF(D1&D2), and required fiber hits above 2.5 photo-electron in every views. Station BACD Road width (mm) 4222 Efficiency DATA Efficiency MC

29 Summary KEK beam test was performed in the fall of Stability of VLPC are checked. –Pedestal peak is within 1 count, –Pedestal width is within 1-2%, –Gain is stable within 2%, and –Noise rate is within 5-8%. Light yield and efficiency are studied with 3GeV/c pion beam without B-Field. Station BACD 3HF Concentration (ppm) 5000 mixture2500 Gain of cassette Low High Measured light yield (p.e.) Light yield from Cosmic-ray test n/a Measured efficiency (%) Expected efficiency (%)