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[CRI RI299] S SFLASH: Absol olute Measurem emen ent o of Fluor ores escen ence ce Yield fro rom Sh Shower P Particles C. Jui 1 , P. Sokolsky 1 , and M. Fukushima 2 . 1 Dept. of Physics and Astronomy, University of Utah, U.S.A. 2

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SLIDE 1

[CRI RI299] S SFLASH: Absol

  • lute

Measurem emen ent o

  • f

Fluor

  • res

escen ence ce Yield fro rom Sh Shower P Particles

  • C. Jui1, P. Sokolsky1, and M. Fukushima2.
  • 1Dept. of Physics and Astronomy, University of Utah, U.S.A.

2ICRR, University of Tokyo, Japan

On Behalf of the sFLASH Collaboration

ICRC 2017

Busan, ROK, Jul 13, 2017

1

Version 7, 7/12/2017 12:20pm Korea time

slide-2
SLIDE 2

sFLAS ASH Collaborati tion

  • n
  • S. Atwood1, K. Belov2, J. Belz1, P. Chen3, C. Field4,
  • M. Fukushima5, J. J. Huang3, M. H. Huang6, D. Ivanov1,
  • C. C. H. Jui1, T.C. Liu6, J. N. Matthews1, J. W. Nam3,
  • M. Potts1, K. Reil4, B. K. Shin7, P. Sokolsky1,
  • S. B. Thomas1, G. Thomson1, S. H. Wang3.
  • 1Dept. of Physics and Astronomy, University of Utah, U.S.A.

2NASA Jet Propulsion Laboratory (JPL), U.S.A. 3LeCosPA, National Taiwan University, Taiwan 4SLAC National Laboratory, U.S.A. 5ICRR, University of Tokyo, Japan 6LeCosPA, National United University, Taiwan 7Faculty of Science, Osaka City University, Osaka, Japan.

2

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SLIDE 3

FLAS ASH ( (~2004) T Thick ck T Target

3

  • 2002-2004 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)

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SLIDE 4

FLA LASH T Thick T Target R Res esult lts

4

Filter Band “None” 310 < λ < 400 nm OF2 370 < λ < 400 nm KG3 330 < λ < 390 nm U360 330 < λ < 380 nm

  • FLASH Thick-Target verified that the relative longitudinal

fluorescence emission follows the predictions of standard physics expectations

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SLIDE 5

New ew E Exper eriment: sFLA LASH @ E ESTA TA

5

SLAC LINAC sFLASH: Endstation A FLASH @ 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)

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SLIDE 6

Motiv tivatio ion f for

  • r A

Absolu

  • lute M

Mea easurement

6

  • 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
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SLIDE 7

New ew S Set etup i in E ESTA

7

Hooverville John Steinbeck, 1939

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SLIDE 8

Variab able De Depth A h Alumina T a Target

8

  • Variable Depth shower target made from the same

alumina bricks previously used for FLASH Thick-

  • Target. Set up on moving tray (shifts left-right)
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SLIDE 9

Shielding

  • The PMTs are minimally shielded from background radiation using

lead bricks – which also restrict/define their field of view

9

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SLIDE 10

Backg kground S Subtrac action

10

  • 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.)
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SLIDE 11

Bea eam M Monit itorin ing

11

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. 18-19

target

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SLIDE 12

Energy De y Deposition S 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. 13-14

12

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SLIDE 13

Data A Analy lysis is

13

  • Waveform from each PMT or coil is recorded by digital
  • scilloscope (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
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SLIDE 14

VERY P Y PRELI ELIMINARY R Y 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

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SLIDE 15

Energy D Dep eposit itio ion p per er b bea eam el elect ctron

15

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

slide-16
SLIDE 16

Pulse areas with Shutter r OPE PEN

(Signa nal + + Backg kgrou

  • und)

16

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

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SLIDE 17

Pulse areas with Shutter r CLOSED

(Background only) y)

17

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

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SLIDE 18

Pulse areas: OPE PEN – CLO LOSED

(Background s subtracted Signal)

18

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

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SLIDE 19

Cal alcu culated Air Fluoresce scence ce Y Yield

(Sig ignal: l: ar arbitrary s scal ale)

19

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

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SLIDE 20

TO DO 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

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SLIDE 21

Summa mary

  • 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. 13-14

  • B. K. Shin (Osaka City University) et al. (Poster Board 083)

The instruments of sFLASH experiment Jul. 18-19

21