Tests of ECAL modules with LED induced light and cosmics

Tests of ECAL modules with LED induced light and cosmics

Ondřej Svoboda for the ECAL group

HADES collaboration meeting XXV, 19 – 23 November 2012 GSI

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Summary of ECAL test setup development since last collaboration meeting:- continuous delivery of new 3 inch photomultipliers

(Hamamatsu R6091)- new mounting construction designed, manufactured and tested- prototype of HV divider for R6091 photomultipliers

constructed and tested- one module with optical fiber and LED diode assembled and

successfully tested (8/2012)- based on this 5 modules with 1.5 inch EMI 9903KB

photomultipliers and 5 modules with 3 inch R6091 photomultipliers assembled, all with optical fiber

- light guide system to drive all 10 modules with one diode assembled

- tests of new TRB based Front-End – see talk of Behruz Kardan- first test of 3 inch photomultipliers – Yuri Sobolev

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Layout of HV divider for 3 inch photomultipliers (Hamamatsu R6091)

- Reason for development and manufacture of own HV divider is the price of original ones…

- First tests show that the divider is comparable with the original Hamamatsu divider (same current, comparable pulse shape and amplitude from the detector).

- To confirm this further tests are needed and will be done in close future.

Produced by CPM Jičín, CZ

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New housing for R6091 3 inch photomultipliers

Magnetic shielding produced in IP Bratislava

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Cosmics measurement3 inch photomultiplier (Hamamatsu

R6091)1.5 inch photomultiplier (EMI

9903KB)

Energy resolution: 5.9% (best case up to now)

Energy resolution: 5.4 % (best case)

ADC (channels)

For measurement used CAMDA system and shaper MA8000

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Tests of diodes for stability monitoring of the ECAL modules

Continuous search for optimal solution from many possibilities:- one diode per module, coupled to lead glass via optical Si fiber

(20 cm)- different light output from each diode (+-50%)

- one diode per sector, light guides to each module- how to distribute the light homogenously to each module?- which fibers, connectors will be used (question of price)?- light source to “power” all sector

- common diode will be most probably weak- high power diode needs higher voltage and current – hard for 10 ns pulses- laser sources – up to now tested one for single mode fibers

- red light (not ideal for photomultiplier) - slow (not able to produce 10 ns pulse of the

same amplitude)- very expensive

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Layout of the ECAL testing setup with LED

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Light guide system for 10 modules

Diode with light distribution system and 10 fibers

Light output from diode

Fiber to lead glass transition

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Measurement with LED diode- very fast measurement (kHz) in comparison with cosmics (~1 signal /3 minutes)- signal from pulser set to get the same detector response as from cosmics

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Yellow curve – detector outputGreen curve – diode input (second peak is reflection

on diode)

10Measurements made by Y. Sobolev on CAMDA system

Measurement with LED diode and 3 inch photomultiplier Hamamatsu R6091

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Summary:

- LED can be used for regular stability monitoring of ECAL during beamtime

- basic assembly of ECAL module driven by LED diode successfully tested

- search for final LED system design

- new housing for R6091 3 inch detectors

- first tests of own HV dividers for R6091 3 inch photomultipliers

- tests of ECAL modules with both types of PMT‘s on cosmics and with LED diode performed

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Thank you for your attention…