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 measurement

3 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…