[CRI299] SFLASH: Absolute Measurement of Fluorescence Yield from Shower Particles

Transcription

1 [CRI299] SFLASH: Absolute Measurement of Fluorescence Yield from Shower Particles C. Jui 1, P. Sokolsky 1, and M. Fukushima 2. 1 Dept. of Physics and Astronomy, University of Utah, U.S.A. 2 ICRR, University of Tokyo, Japan On Behalf of the sflash Collaboration ICRC 2017 Busan, ROK, Jul 13, 2017 Version 7, 7/12/ :20pm Korea time 1

2 sflash Collaboration S. Atwood 1, K. Belov 2, J. Belz 1, P. Chen 3, C. Field 4, M. Fukushima 5, J. J. Huang 3, M. H. Huang 6, D. Ivanov 1, C. C. H. Jui 1, T.C. Liu 6, J. N. Matthews 1, J. W. Nam 3, M. Potts 1, K. Reil 4, B. K. Shin 7, P. Sokolsky 1, S. B. Thomas 1, G. Thomson 1, S. H. Wang 3. 1 Dept. of Physics and Astronomy, University of Utah, U.S.A. 2 NASA Jet Propulsion Laboratory (JPL), U.S.A. 3 LeCosPA, National Taiwan University, Taiwan 4 SLAC National Laboratory, U.S.A. 5 ICRR, University of Tokyo, Japan 6 LeCosPA, National United University, Taiwan 7 Faculty of Science, Osaka City University, Osaka, Japan. 2

3 FLASH (~2004) Thick Target the FLASH experiment measured the fluorescence yield from 30 GeV electron beams at FFTB, SLAC 1. Absolute Measurement of 30 GeV electrons ( Thin Target ) 2. Relative Measurements of yield at different stages of shower development (Thick Target: using alumina as variable-depth shower production target) 3

4 FLASH Thick Target Results Filter Band None 310 < λ < 400 nm OF2 370 < λ < 400 nm KG3 330 < λ < 390 nm U < λ < 380 nm FLASH Thick-Target verified that the relative longitudinal fluorescence emission follows the predictions of standard physics expectations 4

5 New Experiment: ESTA sflash: Endstation A SLAC LINAC FFTB FFTB no longer exists New measurement of absolute fluorescence yield started in 2016 at SLAC in EndStation A (FLASH was run in the old FFTB) 5

6 Motivation for Absolute Measurement Absolute energy scale is important for the interpretation of the high energy suppression seen in the UHECR spectrum TA maintains that suppression consistent with GZK cut-off AUGER has suggested that the suppression is not due to GZK effect 6

7 New Setup in ESTA Hooverville John Steinbeck,

8 Variable Depth Alumina Target Variable Depth shower target made from the same alumina bricks previously used for FLASH Thick- Target. Set up on moving tray (shifts left-right) 8

9 Shielding The PMTs are minimally shielded from background radiation using lead bricks which also restrict/define their field of view 9

10 Background Subtraction A fan-fold window blind (verified to let no UV light through) is used to block the FOV -- controlled remotely by WIFI from a cell phone in the counting house Signal = (data with shutter open data with shutter closed.) 10

11 Beam Monitoring target A calibrated beam coil is used to measure total primary beam charge, upstream of target. See poster by B. K. Shin (ICRR) et al. (Poster Board 083) [CRI135] The instruments of sflash experiment. Jul

12 Energy Deposition Simul. Uses both GEANT and FLUKA based simulation of energy deposition from shower particles in the PMT field-of-view See Poster by J. J. Huang and T. C. Liu (LeCosPA): (Poster Board 032) [CRD114] Geant4 simulation of sflash experiment, Jul

13 Data Analysis Waveform from each PMT or coil is recorded by digital oscilloscope (Tektronix and LeCroy: BW > 2 GHz) Charge extracted from integral area of pulses (baseline subtracted) Mean an error-of-mean extracted from histogram of pulse areas Apply calibration for coil and PMT 13

14 VERY PRELIMINARY RESULTS We did not go beyond ~3 RL because of limitation on radiation levels in ESTA The results shown use a very simple geometrical calculation of the PMT apertures A preliminary PMT calibration is used We show only the results using the GEANT simulation We show results from only ONE version of baseline subtraction The background radiation subtraction takes (binds-open data) (blinds-closed data) 14

15 Energy Deposition per beam electron Energy Deposition per electron (in primary beam before shower) by shower calculated by GEANT 15

16 Pulse areas with Shutter OPEN (Signal + Background) Left: TA PMT (Hamamatsu) identical to those used at TA FD, with pre-amp Right: HiRes PMT (Photonis/Philips) used at High Resolution Fly s Eye AND the original FLASH experiment, no pre-amp 16

17 Pulse areas with Shutter CLOSED (Background only) Left: TA PMT (Hamamatsu) identical to those used at TA FD, with pre-amp Right: HiRes PMT (Photonis/Philips) used at High Resolution Fly s Eye AND the original FLASH experiment, no pre-amp 17

18 Pulse areas: OPEN CLOSED (Background subtracted Signal) Left: TA PMT (Hamamatsu) identical to those used at TA FD, with pre-amp Right: HiRes PMT (Photonis/Philips) used at High Resolution Fly s Eye AND the original FLASH experiment, no pre-amp 18

19 Calculated Air Fluorescence Yield (Signal: arbitrary scale) Left: TA PMT (Hamamatsu) identical to those used at TA FD, with pre-amp Right: HiRes PMT (Photonis/Philips) used at High Resolution Fly s Eye AND the original FLASH experiment, no pre-amp 19

20 TO DO Careful comparison of GEANT and FLUKA results for energy deposition Full ray-tracing simulation of fluorescence emission and propagation to the PMTs Background subtraction double-checked with apparent yield from blinded tubes (blinded cathode) in addition to the blinds-closed data Complete PMT calibration Review baseline subtraction procedure Propose another Beam Run to SLAC? 20

21 Summary Completed a first run for sflash at End Station A, SLAC We have demonstrated so far the resolving power to see evolution in the fluorescence yield with shower age, if there is any Many systematic issues remain to fully understand Another beam run at SLAC? Please go see sflash posters: J. J. Huang and T. C. Liu (LeCosPA): (Poster Board 032) Geant4 simulation of sflash experiment, Jul B. K. Shin (Osaka City University) et al. (Poster Board 083) The instruments of sflash experiment Jul