Diapositiva 1

1
30th International Cosmic Ray Conference, Merida,
July 6, 2007
Electronics and data acquisition system of the
extensive air shower detector array at the
University of Puebla


R. Conde1, O. Martinez1, T. Murrieta1, E. Perez1,
H. Salazar1, L. Villasenor2 1Facultad de
Ciencias Fisico-Matematicas, BUAP, Puebla, Pue.,
72000, Mexico 2Instituto de Fisica y Matematicas,
UMSNH, Morelia, Michoacan, 58040,
Mexico villasen_at_ifm.umich.mx
4. Calibration (Control Experiments)
Abstract Field programmable gate arrays (FPGAs)
are playing an increasing role in DAQ systems in
cosmic ray experiments due to their high speed
and integration and their low cost and low power
consumption. In this paper we describe in detail
the new electronics and data acquisition system
based on FPGA boards of the extensive air shower
detector array built in the Campus of the
University of Puebla. The purpose of this
detector array is to measure the energy and
arrival direction of primary cosmic rays with
energies around 1015 eV. The array consists of 10
liquid scintillator detectors and 6 water
Cherenkov detectors (of 1.86 m2 cross section),
distributed in a square grid with a detector
spacing of 20 m over an area of 4000 m2. The
electronics described also makes use of analog to
digital converters with a resolution of 10 bits
and sampling speeds of 200 MS/s to digitize the
PMT signals. We also discuss the advantages of
discriminating the PMT signals inside the FPGAs
with respect to the conventional use of dedicated
discrimination circuits.
74 pe
Decay electron at 0.17 VEM 41 MeV
a)
Indoors WCD MPV of EM peak 0.12 VEM 29 MeV,
i.e., dominated by knock-on decay electrons
PMT Electron tubes 9353 K
1. Experimental Setup
Muons deposit 240 MeV in 1.20m high water and
only 26 MeV in 13 cm high liquid, while
electrons deposit all of their energy. For 10
Mev electrons we expect Mu/EM24 for
Cherenkov Mu/EM2.6 for Liq. Scint.
EAS-UAP Array (19º N, 90ºW, 800g/cm2)
WCD
Liquid Scint
Outdoors Liquid Scintillator Detector MPV of EM
peak 0.30 VEM i.e., dominated by EM particles
10 MeV
Outdoors WCD MPV of EM peak 0.12 VEM 29 MeV,
i.e., dominated by EM particles 10 MeV
5. New DAQ Electronics
PMT EMI 9030 A
Communication modules
10-bit ADC running at 200MS/s
16-channel discrimination cards
Motherboard based on Xilinx Spartan 2E FPGA
Schematic diagram of ADC and Input/Output scheme
of VHDL program

• 2200m a.s.l., 800 g/cm2. Located at Campus
  Universidad Autonoma
• de Puebla
• Hybrid Liquid Scintillator Detectors and water
  Cherenkov Detectors
• Energy range 1014 - 1016 eV

6. Results
2. Old DAQ Electronics
ADC sampling at 200 MS/s Two ADCs running 180
out of phase at 100 MS/s each
Trigger Coincidence of 4 central detectors
(40mx40m) NIM y CAMAC. Use of digital
Osciloscopes as ADCs Rate 80 eventos/h
Charge vs risetime for a WCD located indoors
Charge distribution for background muons
Amplitude vs risetime for a WCD located outdoors
3. Monitoring
Use CAMAC scalers to measure rates of single
partícles on each detector. Day-night
variations lt10
Conclusions We have described the new DAQ system
for the EAS-UAP air shower array. This new system
takes advantage of the recent progress on on-chip
fast ADCs and the ever faster and more powerful
FPGAs. We have achieved single channel sampling
rates of 200 MS/s at 10 bit by combing these
modern advanced with the flexibility provided by
on-chip programming using VHDL. The use of cheap
GPS embedded receivers allows us to attach a
precise time tag to each L2 trigger event for
further off-line analyses.
s/mean around 3
References J. Cotzomi, E. Moreno, T. Murrieta,
B. Palma, E. Pérez, H. Salazar, and L.
Villaseñor, The Water Cherenkov Detector Array
for studies of cosmic rays at the University of
Puebla, Nucl. Instr. and Meth. in Phys. Res. A.,
Volume 553, Issues 1-2 (2005) Pages 290-294. H.
Salazar, O. Martínez, E. Moreno, J. Cotzomi, L.
Villaseñor, O. Saavedra, Results from the Puebla
extensive air showed detector array, Nuclear
Physics B (Proc. Suppl.) 122 (2003) 251-254. J.
Cotsomi, O. Martinez, E. Moreno, H. Salazar and
L. Villaseñor, Extensive Air Shower Array at the
University of Puebla for the Study of Cosmic
Rays, Rev. Mex. Fis. Vol. 51 No. 1 (2005)
38-46. L. Villaseñor and H. Salazar, Separation
of Cosmic-Ray Components in Water Cherenkov
Detectors, Nucl. Instr. and Meth. in Phys. Res.
A., Volume 553, Issues 1-2 (2005) 295-298.