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Preliminary Analysis Results of PoGO Argonne Beam Test

Preliminary Analysis Results of PoGO Argonne Beam Test. December 10, 2003 Tsunefumi Mizuno mizuno@SLAC.Stanford.EDU. Data Files. 212 data files and the log (txt and pdf format) can be obtained through the web: http://www.slac.stanford.edu/~mizuno/PoGO/Argonne/index.html

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Preliminary Analysis Results of PoGO Argonne Beam Test

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  1. Preliminary Analysis Results of PoGO Argonne Beam Test December 10, 2003 Tsunefumi Mizuno mizuno@SLAC.Stanford.EDU ArgonneResult_2003-12-10.ppt

  2. Data Files • 212 data files and the log (txt and pdf format) can be obtained through the web: • http://www.slac.stanford.edu/~mizuno/PoGO/Argonne/index.html • “Digitized data files”, where peak voltage is converted in 10 bit integer will be used in the following analysis. • Data files are also available via ftp: ftp as 'anonymous' to ftp.slac.stanford.edu then "cd groups/astro_gam/PoGO/Argonne” ArgonneResult_2003-12-10.ppt

  3. Run Summary • Coincidence Trigger (every 15 degree): • run048-073: 83.5 keV run • run106-149: 60.2 keV run • run164-190: 73.2 keV run • Ch4 Trigger (every 30 degree, does not cover the whole azimuth angle): • run191-197: 73.2 keV run • run210-212: 83.5 keV run • Calibration Run: • run088,090-096: 83.5 keV run • run090-105,150-156: 60.2 keV run • run157-163: 73.2 keV run • For more details, please read the log in http://www.slac.stanford.edu/~mizuno/PoGO/Argonne/index.html. • We also took the BG data but does not use them in this preliminary analysis report. BG is small and does not affect the results very much. ArgonneResult_2003-12-10.ppt

  4. Calibration Run • Fit data with gaussian + linear function • Use channel/energy conversion factors for 73.2 keV run in the following analysis. Conversion factors for 83.5 keV run and 60.2 keV run are consistent with them within 2%. • ch1: p=326.5, sigma=34.9 (FWHM:25.1%), f=4.46 • ch2: p=331.5, sigma=32.3 (FWHM:22.9%), f=4.53 • ch3: p=334.9, sigma=39.5 (FWHM:27.7%), f=4.58 • ch4: p=317.7, sigma=41.5 (FHWM:30.7%), f=4.34 • ch5: p=350.9, sigma=49.1 (FHWM:32.9%), f=4.79 • ch6: p=326.0, sigma=35.5 (FHWM:25.6%), f=4.45 • ch7: p=377.2, sigma=43.6 (FHWM:27.2%), f=5.15 ArgonneResult_2003-12-10.ppt

  5. Definitions • We defined that xy plane is normal to the scintillator principle axis. • Scintillators are numbered from 1 to 7. Central scintillator is number 4. • Beam goes from +z to -z. Polarization vector is along x-axis. • We rotated the detectors. When we rotate them by 30 degree, scintillator number 2 is along the y axis. y 30degree polarization vector 1 2 3 4 5 x Beam Direction 6 7 ArgonneResult_2003-12-10.ppt

  6. 73.2 keV Ch4 Trigger Run (1) • Event selection criteria: • Detection threshold:2 keV • 2 scintillators are with hit (one hit in central scintillator) • depE4<=40keV, depE4<=0.5*totE • 45 keV <= totE <= 100 keV Total deposit energy seems to be ~70 keV, a little bit smaller than the beam energy. ArgonneResult_2003-12-10.ppt

  7. 73.2 keV Ch4 Trigger Run (2) ch3 ch7 ch5 Modulation Factor ~(1650-650)/(1650+650) ~43% ch1 ch2 ch6 ArgonneResult_2003-12-10.ppt

  8. Trigger Efficiency (1) • During the beam test, we found that trigger efficiency is not 100% for coincidence trigger run and it varies among channels. E.g., efficiency of ch6 seemed to be ~2/3 of others. • To obtain “unbiased” events, we performed ch4 trigger run, and the results were shown in page 7. By comparing them with coincidence trigger run of the same energy and rotation angle, we can evaluate the relative trigger efficiency of each channel. ArgonneResult_2003-12-10.ppt

  9. Trigger Efficiency (2) • Use 73.2 keV runs. • Efficiency of ch7 is normalized to 1. • Errors shown are statistical errors only. • Fitting by constant (dof=5): • ch1:0.843+-0.017, chi2=6.6 • ch2:0.979+-0.021, chi2=8.7 • ch3:0.987+-0.021, chi2=6.1 • ch5:0.803+-0.018, chi2=5.7 • ch6:0.621+-0.013, chi2=7.6 • Chi2/dof>=1. Probably there are systematic errors comparable to statistical ones. ch2 ch3 ch1 ch5 ch6 ArgonneResult_2003-12-10.ppt

  10. 73.2 keV Coincidence Trigger Run(1) • Selection criteria are the same as those for ch4 trigger run. • Total deposit energy seems to be a little bit smaller than beam energy. • We observe a small dip in energy deposit in scintillator number 4 (around 10 keV). ArgonneResult_2003-12-10.ppt

  11. 73.2 keV Coincidence Trigger Run(2) • Selection criteria are the same as those for ch4 trigger run. • Trigger efficiency is not collected. • Normalized based on the number of triggers. ch3 ch2 ch7 ch5 ch1 ch6 ArgonneResult_2003-12-10.ppt

  12. 73.2 keV Coincidence Trigger Run (3) • Selection criteria are the same as those for ch4 trigger run. • Trigger efficiency is collected. • Normalized based on the number of selected events. ch3 ch2 ch7 ch5 ch1 ch6 • MF~(2400-1000)/(2400+1000)~41% • Small (but statistically significant) difference between ch1/ch7, ch2/ch6, and ch3/ch5. Due to geometry? Error of trigger efficiency? ArgonneResult_2003-12-10.ppt

  13. 83.5 keV Coincidence Trigger Run(1) • Selection criteria: Eth=2keV, 2hits (one in central scint.), depE4<=45keV, depE4<=0.5*totE, 55keV<=totE<=110 keV. • Trigger efficiency is not collected. • Normalized based on the number of triggers. ch3 ch2 ch7 ch5 ch1 ch6 ArgonneResult_2003-12-10.ppt

  14. 83.5 keV Coincidence Trigger Run (2) • Selection criteria are the same as those in the previous page. • Trigger efficiency is collected. • Normalized based on the number of selected events. ch3 ch6 ch7 ch5 ch2 ch1 • MF~(2400-1000)/(2400+1000)~41% • Small difference between ch1/ch7, ch2/ch6, and ch3/ch5. ArgonneResult_2003-12-10.ppt

  15. 60.2 keV Coincidence Trigger Run(1) • Selection criteria: Eth=2keV, 2hits (one in central scint.), depE4<=35keV, depE4<=0.5*totE, 35keV<=totE<=90 keV. • Trigger efficiency is not collected. • Normalized based on the number of triggers. ch3 ch2 ch7 ch5 ch1 ch6 ArgonneResult_2003-12-10.ppt

  16. 60.2 keV Coincidence Trigger Run (2) • Selection criteria are the same as those in the previous page. • Trigger efficiency is collected. • Normalized based on the number of selected events. ch3 ch1 ch2 ch7 ch5 ch6 • MF~(2400-1000)/(2400+1000)~41% • Difference between ch1/ch7, ch2/ch6 and ch3/ch5. Somewhat larger than those seen in 73.2keV/83.5keV runs. ArgonneResult_2003-12-10.ppt

  17. Summary • We applied preliminary event selection criteria to data. Modulation factor for ch4 trigger run of 73.2 keV is 40-45% (pages 6 and 7). • We evaluated the rigger efficiency of ring scintillators. There could be some systematic errors, but they are small and comparable to statistical ones (pages 8 and 9). • We took the trigger efficiency into account for coincidence trigger runs and obtained clear modulation curves. MF (40-45%) does not depend on the beam energy very much and is consistent with that of ch4 trigger run (pages 10-16). • We observe small difference between ch1/ch7, ch2/ch6 and ch3/ch5. It could be due to geometry and/or errors of trigger efficiency (pages 12, 14 and 16). • We also found some strange features (probably not a big problem): • Total energy deposition is ~5% smaller than the beam energy. • We observed small dip in energy deposition of ch4 (central scintillator) for coincidence trigger. • Future Plan: • Understand features mentioned above (if possible). • Improve event selection. • Compare data with simulation prediction. ArgonneResult_2003-12-10.ppt

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