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Multi-sector scintillation detector for investigations of Extensive Air Showers

Multi-sector scintillation detector for investigations of Extensive Air Showers. E.E. Yanson BARS-EAS Collaboration IHEP, Protvino, Russia MEPhI, Moscow, Russia EEYanson@mephi.ru.

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Multi-sector scintillation detector for investigations of Extensive Air Showers

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  1. Multi-sector scintillation detector for investigationsof Extensive Air Showers E.E. Yanson BARS-EAS Collaboration IHEP, Protvino, Russia MEPhI, Moscow, Russia EEYanson@mephi.ru

  2. In standard technique of EAS registration, the distributed systems of detectors are used. Depending on a solved problem, the shower array is combined with the central detector. For collaboration BARS-EAS the central detector is liquid-argon spectrometer BARS located in IHEP, Protvino. BARS-EAS We tried to create simple and cheap detector.

  3. Shower detector • Scintillation assembly with area 1 sq. m. • Thickness of plastic is 20 mm. • Light is collected by means of wavelength shifter bars. • Fast PMT with small diameter photocathode. • Front-end electronics (controller, QDC, TDC, HV converter,thermosensors, etc.). • Total weight ~ 70 kg. Therefore deployment of the array on the roofs of the buildings is possible.

  4. Scheme of scintillation assembly • octagonal shape • 8 sectors • 8 shifter bars which are fixed between these sectors • PMT is located in the centre of the detector PMT

  5. Scintillation assembly

  6. Scintillation assembly The shifter technique allows to use PMT with small diameter photocathode. The central location and use of fast PMT provide a good time resolution of our detector. Accuracy of time determination ~ 3 ns.

  7. Shifter bars

  8. Scheme of light collection Shifter turns light and directs it exactly to photocathode PMT = 30 mm

  9. Central part • cocraft-type high voltage converter • preampliphier for anode • preampliphier for 8th dynode • preampliphier for 12th dynode

  10. System of temperature stabilization The system of temperature stabilization must provide a constant temperature inside the detector. • Thermo-insulating box of rigid polyfoam. • Two thermosensors. • Heater. • Bottom level programme of the heater control (located in the detector). • Top level programme of the heater control (located in central computer). This program permanently requests the data of the thermosensors for check correctness of actions of the controller.

  11. Rigid polyfoam Thickness of the walls is 7 cm Thermo-insulating box

  12. Top of the box,heater The fan pumps the air through the heating element. Thermotube for cold air. Thermotube for hot air.

  13. Temperature stabilization 15 14 5 - 7 min

  14. Detectorhousing 0.7 mm zinced steel Communicationcabie This detector can work on distance up to 1 km from the central computer.

  15. Communications QDC TDC LED HV Thresh Outer electronics of the array Front-end electronics of the detector Communication cable

  16. EAS trigger The ANSWER signal is initiated by the coincidences of signals shower detectors (then timer stops). The array detector is considered has worked if the anode signal of PMT exceeds the threshold of 0.5 MIP. In this case, the timer is started and signal REQUEST is sent.

  17. Front-end electronics Front-end electronics of the detector provides the possibility to work in several operating modes (registration, monitoring, calibration). It includes: • Controller (microcontroller 8051). • Measuring part. Using two 12-bit QDC (for two dynodes) allow to provide dynamic range of measured signals from 1 to 104 particles in the detector. 12-bit TDC provides accuracy of time interval ~ 1 ns. • System of calibration (LED based). • HV-converter. • First-level trigger logics • Communication system is based on CAN-open standard.

  18. Front-end electronics

  19. Outer electronics of the array Allows to operate up to 48 detectors PC for DAQ. WinXP PC for trigger. FreeDOS

  20. Response of the detector To provide a good energy resolution, it was necessary: • To reduce a loss of the light from plastic and shifters. We applied "tyvek" which covers top and bottom sides of each scintillation plate; • To select the scintillation plates with identical output of light; • To get the uniformity of the response for any co-ordinate of the scintillation plates. Uniformity of the response was estimated by means of comparison of average values of amplitude spectra for muons passing through different areas of the detector.

  21. Shaded masks Without a mask, the amplitude in the near-PMT zone is 1.6 times higher than on the edge. Mapping of shaded masks for sectors is done by means of the ink printer under control of the program with a pre-set table of blacking.

  22. Single vertical muon • Bicron 404A • 12.7 mm • ~ 50 ph.e. • A = 164 • A – Ped = 58 • FWHM = 32 • FWHM = 0.55 A - Ped

  23. Conclusion • The multi-sector detector has a good time and amplitude resolution, low weight and low cost. • Front-end electronics allows to obtain a dynamic range from 1 up to 10000 particles, 1 ns timer clock, and control the temperature inside the detector. • In the control system, various modes of calibration and operation are foreseen.

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