The Fluorescence detector Array of Single-pixel Telescopes (FAST) is a design concept for the next generation of ultrahigh-energy cosmic ray (UHECR) observatories, addressing the requirements for a large-area, low-cost detector suitable for measuring the properties of the highest energy cosmic rays. In the FAST design, a large field of view is covered by a few pixels at the focal plane of a mirror or Fresnel lens. Motivated by the successful detection of UHECRs using a prototype comprised of a single 200 mm photomultiplier-tube and a 1 m2 Fresnel lens system [Astropart.Phys. 74 (2016) 64-72], we have developed a new full-scale prototype consisting of four 200 mm photomultiplier-tubes at the focus of a segmented mirror of 1.6 m in diameter. In October 2016 we installed the full-scale prototype at the Telescope Array site in central Utah, USA, and began steady data taking. We report on first results of the full-scale FAST prototype, including measurements of artificial light sources, distant ultraviolet lasers, and UHECRs. 35th International Cosmic Ray Conference — ICRC2017 18th July, 2017 Bexco, Busan, Korea

1. First results from the full-scale prototype for the
Fluorescence detector Array of Single-pixel Telescopes
Toshihiro Fujii (fujii@icrr.u-tokyo.ac.jp), Max Malacari, Justin Albury,
Jose A. Bellido, John Farmer, Aygul Galimova, Pavel Horvath, Miroslav
Hrabovsky, Dusan Mandat, Ariel Matalon, John N. Matthews, Maria
Merolle, Xiaochen Ni, Libor Nozka, Miroslav Palatka, Miroslav Pech,
Paolo Privitera, Petr Schovanek, Stan B. Thomas, Petr Travnicek
(FAST Collaboration, https://www.fast-project.org)
July 17th 2017, ICRC 2017 in Busan
1

2. Fluorescence detector Array of Single-
pixel Telescopes (FAST)
Ø Target: 1019.5 eV, ultrahigh-energy cosmic rays
(UHECRs) and neutral particles (γ-rays, neutrinos)
Ø Huge target volume ⇒ Fluorescence detector array
2
Fine pixelated camera
Low-cost, a few pixels telescope
Too expensive to cover a huge area.
Shower profile reconstruction
using given geometry

3. Fluorescence detector Array of Single-
pixel Telescopes (FAST)
3
Ø Each telescope: 4
PMTs, 30°×30° field of
view (FoV).
² Reference design: 1
m2 aperture, 15°×15°
FoV per PMT
Ø Each station: 12
telescopes, 48 PMTs,
30°×360° FoV.
Ø Deploy on a triangle
grid with 20 km
spacing, like “Surface
Detector Array”.
Ø 500 stations ⇒ 150,000
km2
Ø Geometry: radio,
surface detector or
coincidence of three
stations.

4. UHECR measurements with FAST prototypes
Ø Confirmed milestones with EUSO-TA
optics + FAST camera
² Stable operation under high night sky
backgrounds.
² UHECR detections.
o T. Fujii et al., Astropart.Phys. 74 (2016)
64-72, arXiv: 1504.00692
Ø Next milestones with the full-scale
FAST prototype
² Establish the FAST sensitivity.
² Detect a shower profile including Xmax
with FAST.
4
FAST - today
Accepted for publication
in Astroparticle Physics
EUSO-TA optics
+ FAST camera
Full-scale FAST
prototype
Cosmic ray
~1018.0 eV
Vertical Laser
~1019.3 eV
Joint laboratory of optics, Czech republic,
Olomouc

5. Full-scale FAST prototype
FAST - progress in design and construction
UV Plexiglass Segmented primary mirror8 inch PMT camera
(2 x 2)
1m2 aperture
FOV = 25°x 25°
variable
tilt
Joint Laboratory of Optics Olomouc – Malargue November 20153
Prototype - October 2015
15°
45°
UV band-pass
filter
5
Ø 4 PMTs (8 inch, R5912-03MOD, base
E7694-01), UV band-pass filter
(ZWB3)
Ø Segmented mirror of 1.6 m diameter
PMT installation
UV band-pass filter
Mirror assembly
Time lapse movies produced by Max Malacari, Dusan Mandat

6. 6
Telescope Array site
at Utah
①
②
③
④
⑤
⑥
⑦
⑩
⑪
⑨
⑧

7. FAST DAQ Setup
Ø DAQ synchronized with the
external trigger of TA FD
² 12 bit, 50 MHz sampling
² Sum up 5 adjacent bins to be 10
MHz
² 80 µs trigger window
Ø Field-of-view of this prototype
is set to detect a vertical UV
laser signal at a distance of
20.85 km.
7
PMT1
PMT3
PMT2
PMT4
Laser event

8. Department of Physics, University of Chicago
FIG. 12. SPE peak height distribution used to set discrimi-
nator threshold value. The pedestal ends at around a height
of 350 ADC counts. Dividing this by the 4095 dynamic range
of the FADC gives a discriminator threshold of ⇡ 85 mV.
in wavelength. A NIST calibrated photodiode provides
the absolute calibration for the incident light flux, deter-
mining N through a powermeter readout. The flux is
reduced to the SPE level measurable by the PMT using
an integrating sphere of known transmission and incorpo-
rating the light attenuation coe cient of the apparatus13
,
↵ = (5.828 ± 0.018) ⇥ 10 4
. Eq. 5 can thus be rewritten:
✏ =
Npe
N
= Npe ⇥
hc
Pt ↵
(6)
where is the wavelength, P is the powermeter read-
ing, and t is the read out time for each step. Typical
Wavelength [nm]
0 100 200 300 400 500 600 700
Efficiency[%]
0
2
4
6
8
10
12
14
16
18
20
22
Detection Efficiency: FAST PMTs
Hamamatsu (Scaled)
PMT ZS0025
PMT ZS0024
PMT ZS0022
PMT ZS0018
18. HV = 2169V, Disc = 38mV, x20 Amp
22. HV = 2252V, Disc = 50mV, x20 Amp
24. HV = 2266V, Disc = 85mV, x20 Amp
25. HV = 2000V, Disc = 44mV, x20 Amp
FIG. 13. Detection e ciency results with Hamamatsu m
surement for comparison.
the powermeter and monochromator initialized, any
maining lights in the lab are switched o↵. The comp
in the lab is accessed remotely to begin data acqu
tion. The DAQ program controls the monochrom
and powermeter. It obtains and averages 10,000 re
ings from the powermeter over 10 s for a given step;
error, P , is calculated in quadrature from Poisson sta
tics on both powermeter readings, lamp signal and b
ground. The lamp background corresponds to when
powermeter values are read out while the monochro
tor shutter is kept closed; the lamp signal is obtained
an open shutter. The final power value used in ca
lating detection e ciency is the di↵erence between th
(P = Plamp,sig Plamp,bkd). The PMT rate, R, is ca
lated in a similar way, with open and closed shutters
responding to signal and background, respectively.
detection e ciency is calculated using Eq. 6, and
statistical error is given by Eq. 7, 8, 9:
P = P ⇥
s
(
Plamp,sig
Plamp,sig
)2 + (
Plamp,bkd
Plamp,bkd
)2
s
Rsig 2 Rbkd 2
PMT Calibrations
8
used in AIRFLY experiment
Astropart.Phys. 42 (2013)
90–102
ement
MOD PMTs used consist
in base, and have a HV
of the PMTs is prefixed
T number. We test the
obtaining a single photo-
ement. We place a single
tput of the dual-channel
t of the PMT. The LED
kHz; typical LED ampli-
V and ⇡ 100 ns.
PMT is connected to the
lifier; the two resulting
he FADC input and first
ctively. The PMT anode
DC converts the signal to
0 to 4095 (12-bit range).
Time (2 ns)
1000 1200 1400
Time (2 ns)
1000 1200 1400
Time (2 ns)
1000 1200 1400
PE event (top); SPE signal
PMT ZS0018 PMT ZS0022
Sigma 28.6±1254
Integrated counts
0 2000 4000 6000 8000 10000 12000
20
40
60
80
100
120
Sigma 28.6±1254
Integrated counts
−200 −100 0 100 200
0
20
40
60
80
100
Sigma 44.7±1641
Integrated counts
−2000 0 2000 4000 6000 800010000120001400016000
0
50
100
150
200
Sigma 44.7±1641
PMT ZS0024 PMT ZS0025
Entries 23504
Mean 2111
RMS 2691
/ ndf2
175.6 / 85
Constant 2.3±184.8
Mean 30.6±4582
Sigma 21.9±1933
Integrated counts
0 5000 10000 15000 20000 25000
Entries
200
400
600
800
1000
1200
1400
Entries 23504
Mean 2111
RMS 2691
/ ndf2
175.6 / 85
Constant 2.3±184.8
Mean 30.6±4582
Sigma 21.9±1933
Entries 23504
Mean 0.857
RMS 55.09
/ ndf2
0 / −3
Constant 1.4±184.8
Mean 1.4±4582
Sigma 8350.8±1933
Integrated counts
−200 −150 −100 −50 0 50 100 150
Entries
0
20
40
60
80
100
120
140
160
Entries 23504
Mean 0.857
RMS 55.09
/ ndf2
0 / −3
Constant 1.4±184.8
Mean 1.4±4582
Sigma 8350.8±1933
Entries 43157
Mean 4210
RMS 6062
/ ndf2
263.4 / 104
Constant 2.1±161.5
Mean 34.5±9949
Sigma 42.9±2982
Integrated counts
0 5000 10000 15000 20000 25000
Entries
200
400
600
800
1000
1200
Entries 43157
Mean 4210
RMS 6062
/ ndf2
263.4 / 104
Constant 2.1±161.5
Mean 34.5±9949
Sigma 42.9±2982
FIG. 7. Integrated count distribution of SPE signa
ing pedestal (left peak) and SPE peak fitted to a
for all PMTs.
After specifying the signal region for the aver
signal, we obtain a SPE integrated count dis
sometimes displayed as a charge distribution. S
events will have no photoelectrons (i.e. no ch
expect a peak centered around zero, called the
We then have a SPE peak that we fit to a Ga
extract a mean SPE value (Fig 7). This parame
for other characterization measurements. The
the range in which the tail end of the pedestal
the tail end of the SPE peak. A discriminato
introduced to remove the pedestal, leaving only
spectrum. Fig. 8 shows logic for the SPE meas
Characteristics like the peak-to-valley (P:V)
Single photo
electron
Detection efficiency
(QE×CE)
KICP, Univ. of Chicago
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
0
200
400
600
800
1000
1200
PMT 1
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
0
200
400
600
800
1000
1200
PMT 3
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
0
200
400
600
800
1000
1200
PMT 2
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
0
200
400
600
800
1000
1200
PMT 4
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
-40
-30
-20
-10
0
10
20
30
40
PMT 1
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
-40
-30
-20
-10
0
10
20
PMT 3
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
-30
-20
-10
0
10
20
30
PMT 2
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
0
50
100
150
200
250
300
PMT 4
YAP pulser (YAlO3:Ce
scintillator + 241Am
source) attached on
each PMT surface
Ultraviolet
LED
illuminating
the front of
the camera
Wavelength [nm]

9. Telescope alignments and Raytracing simulation
2017JIN
Wavelength [nm]
260 280 300 320 340 360 380 400 420
Efficiency[%]
0
10
20
30
40
50
60
70
80
90
100
Mirror reflectivity
Filter transmission
Total efficiency
The typical spectral reflectance of the FAST mirror between 260 nm and 420 nm, along with the
ansmission of the UV band-pass filter. The resultant total optical e ciency is shown in black.
9
Further information in poster 140, PoS (ICRC2017) 389 on July 18-19th,
or recently published paper, D. Mandat et al., JINST 12, T07001 (2017)
11
Optical simulation status
FAST Simulation - example
- PSF (7.5deg diagonal) aperture input 0.5W 0.43W/PMT1, 0.001W/PMT234 (eff: 86%)
Telescope alignment w/ stars
Mirror alignment
by 2 LEDs
Mirror reflectance and
filter transmittance
Raytrace simulation
for spot sizes and
angular responses
PMT2
PMT4
focal plane 50 mm offset

10. Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
-30
-20
-10
0
10
20
30
40
PMT 1
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
-30
-20
-10
0
10
20
30
40
PMT 3
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
-20
-10
0
10
20
30
PMT 2
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
-20
-10
0
10
20
30
40
PMT 4
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
0
5
10
15
20
PMT 1
PMT 2
PMT 3
PMT 4
Distant vertical laser comparison in Data/MC
10
Single event
Average of 284 triggers
Ø Ultraviolet vertical laser at a distance
of 20.85 km, E = 4.4 mJ, λ = 355 nm,
Ø Every 30 minutes during a clear
night, equivalent to a UHECR with
~1019.5 eV
Ø Calculate expected signal by
simulation and good agreement with
observed data.
Ø Monitoring the transparency of the
atmosphere.
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
0
5
10
15
20
25
PMT1
PMT2
PMT3
PMT4
Simulation (Preliminary)

11. Event data with the full-scale FAST prototype
Ø Data on Oct.5th
2016
Ø 62194 triggers
² PMT1,2,3,4
² Circle size =
significance
Ø Remove airplane
(35 µs) and
laser events (time
information).
Ø Two significant
signal in PMTs
Ø 90 events
survived
Ø 2 events found as
candidates.
Ø Check TAFD
reconstruction.
11
Time (100 ns)
0 100 200 300 400 500 600 700 800
pN
-20
0
20
40
60
Time (100 ns)
0 100 200 300 400 500 600 700 800
pN
-30
-20
-10
0
10
20
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
-20
0
20
40
60
80
100
120
140
PMT 2
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
-20
-10
0
10
20
30
40
PMT 4
Airplane
Laser
All triggers
Selected triggers

12. First lights from UHECRs
12
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
-40
-20
0
20
40
60
PMT 1
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
-20
-10
0
10
20
30
40
PMT 3
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
-40
-30
-20
-10
0
10
20
30
40
50
PMT 2
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
-30
-20
-10
0
10
20
30
40
PMT 4
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
0
500
1000
1500
2000
PMT 1
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
0
50
100
150
200
250
300
350
PMT 3
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
0
200
400
600
800
1000
PMT 2
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
0
50
100
150
200
250
300
PMT 4
Event 387: log10(E(eV)): 18.68, Zen: 61.0◦
, Azi: 63.3◦
,
Core(11.86, -11.50), Rp: 3.52, Psi: 42.8◦
, Xmax: 1113 g/cm2
FoV(1407 - 1769), Date: 20161005, Time: 06:07:38.800548560
Event 388: log10(E(eV)): 17.96, Zen: 38.8◦
, Azi: -19.6◦
,
Core(8.90, -17.03), Rp: 9.44, Psi: 82.6◦
, Xmax: 768 g/cm2
FoV(498 - 1017), Date: 20161005, Time: 06:30:06.947113522
Event 389: log10(E(eV)): 17.83, Zen: 4.7◦
, Azi: 115.2◦
,
Core(14.23, -5.41), Rp: 7.18, Psi: 86.7◦
, Xmax: 656 g/cm2
FoV(473 - 850), Date: 20161005, Time: 06:35:10.462924009
Event 393: log10(E(eV)): 18.14, Zen: 31.6◦
, Az
Core(6.02, -6.69), Rp: 11.96, Psi: 102.1◦
, Xmax: 76
FoV(373 - 991), Date: 20161005, Time: 06:51:48.29284
Event 394: log10(E(eV)): 18.69, Zen: 61.2◦
, Azi
Core(9.58, -20.15), Rp: 9.27, Psi: 57.3◦
, Xmax: 102
FoV(829 - 1221), Date: 20161005, Time: 06:53:27.0113
Event 395: log10(E(eV)): 18.26, Zen: 17.7◦
, Azi:
Core(13.53, -2.14), Rp: 10.39, Psi: 98.2◦
, Xmax: 76
FoV(303 - 890), Date: 20161005, Time: 06:53:43.90953
① 2016/10/05 06:37:49.525424540
② 2016/10/05 10:25:50.781802380
TAFD reconstruction
logE = 18.08, Rp = 2.40 km
Too close, Cherenkov
dominated event.

13. Remote operation with FAST
13
18 events found by January (120 hours)
Ø Fully remote operation
² Automated shutdown procedure
² Monitor a shutter by an infrared
camera
o IP camera(PIC1008WN), relay
module (ETH002)
Ø Total operation time reaches 201
hours by July.
Open Close
Highest event, E=1018.55 eV,
Rp=3.0 km by TA FD
Remote operation
Operation at site

14. Data analysis and simulation study
14
Geometry (given
by TASD)
Shower Profile
(FAST)
✦ Energy: 10%, Xmax : 35 g/cm2 at 1019.5
eV. Independent cross-check of energy
and Xmax scale of TA/Auger
Simula(on
32
EeV
+
FAST only reconstruction
FAST hybrid reconstruction
✦ Fluorescence detector array with
a 20 km spacing. Reconstruct
geometry and profile
56 EeV Simulation

15. Summary and future plans
Ø Installed the full-scale FAST prototype at
Telescope Array site and started remote
operation.
² Detect a distant vertical laser.
² Detect UHECRs.
² Stable observation with remote controlling.
Ø We will continue to operate the prototype
and search for UHECR in coincidence with
the TA detectors.
Ø We plan to install two more telescopes in
September 2017.
² Total FoV will be 75 degree × 25 degrees
² Upgrade the electronics for self trigger with
FAST.
Ø Install all sky camera to check the weather for
automated operation.
Ø Plan to install at Auger site in the future for
cross calibration between experiments.
Ø New collaborators and applications are
welcome.
15
Time (100 ns)
0 100 200 300 400 500 600 700 800
/(100ns)p.e.N
0
5
10
15
20
PMT 1
PMT 2
PMT 3
PMT 4
Rain
Snow
Fog

16. Backup
16

17. 17

18. Size as a reference
Ø 100,200 km²
18