Construction of the hadronic calorimeter prototype for ILC

Construction of the hadronic calorimeter prototype for ILC (CALICE collaboration) or experience with Geiger mode operating multipixel photodiodes (Si. PM) V. Rusinov, ITEP, Moscow Representing the CALICE collaboration 10 -th INTERNATIONAL CONFERENCE ON INSTRUMENTATION FOR COLLIDING BEAM PHYSICS Novosibirsk, February 28 -March 5, 2008 1

Contents • scintillator layers creation • main impressions from Si. PM • possible further applications • desirable properties for new generation of Si. PM • conclusions 2 V. Rusinov 10 -th INTERNATIONAL CONFERENCE ON INSTRUMENTATION FOR COLLIDING BEAM PHYSICS Novosibirsk, March 4, 2008

Si. PM – common name and the detector from this producer - Producer: MEPh. I-Pulsar -1× 1 mm 2, 1156 pixel -Operating voltage: 30 -70 Volts -More than 12000 Si. PMs were studied 42 m 20 m pixel h LED + β-source Al Depletion Region 2 m R 50 Substrate Ubias See yesterday’s talks by D. Renker and Yu. Musienko V. Rusinov 10 -th INTERNATIONAL CONFERENCE ON INSTRUMENTATION FOR COLLIDING BEAM PHYSICS Novosibirsk, March 4, 2008 3

Detector unit: Scheme of assembling - 3× 3, 6× 6, 12× 12 cm 2 - uniformity - cross-talk - drop between tiles 4 V. Rusinov 10 -th INTERNATIONAL CONFERENCE ON INSTRUMENTATION FOR COLLIDING BEAM PHYSICS Novosibirsk, March 4, 2008

Test bench for Si. PM parameter measurement Set up is realized in CAMAC standard LED driver It includes: PC driven generator 16 channel computer driven power supply to feed Si. PM’s - 5 m. V resolution - 110 V max - 100 μA maximal output current 16 channel computer read-out digital voltmeter to monitor - Si. PM bias voltage - Si. PM current - temperature during test measurement accuracy voltage – 5 m. V current – 5 n. A temperature – 0. 2 O DATA Digital voltmeter BASE Remote control 16 channel power supply Steering program ……. 16 ch X~100 PMT 12 bit gate PC driven generator to produce LED and random triggers and ignite LED ADC Tested Si. PMs 16 channel 12 bit ADC 0. 25 p. C/count sensitivity 16 ch amp 16 ch 12 bit ADC PMT to monitor LED light 15 Si. PMs can be tested simultaniously Measurements are done at 2 k. Hz trigger rate A software package was developed to make easy interface between user and hardware, to perform measurements and to save results in data base 5 V. Rusinov 10 -th INTERNATIONAL CONFERENCE ON INSTRUMENTATION FOR COLLIDING BEAM PHYSICS Novosibirsk, March 4, 2008

Picture from PC screen, one of 8 steps of HV tuning. 6 V. Rusinov 10 -th INTERNATIONAL CONFERENCE ON INSTRUMENTATION FOR COLLIDING BEAM PHYSICS Novosibirsk, March 4, 2008

Si. PM parameter distributions Result of selection Rejected reason: Gain – 2. 8% Noise at ½ pixel – 5. 5% Noise at ½ MIP – 22. 6% Cross talk – 3. 5% Current – 0. 5% Current RMS – 1. 4% Yield of good Si. PM’s > 70% 7 V. Rusinov 10 -th INTERNATIONAL CONFERENCE ON INSTRUMENTATION FOR COLLIDING BEAM PHYSICS Novosibirsk, March 4, 2008

What detector has been used, comparison with other Si. PM (See the talk of Yu. Musienko with recent Si. PM achievements) Characteristics of Si. PM used for CALICE HCAL prototype are far from today's record values But… V. Rusinov 10 -th INTERNATIONAL CONFERENCE ON INSTRUMENTATION FOR COLLIDING BEAM PHYSICS Novosibirsk, March 4, 2008 8

1. Do not forget that the work on HCAL prototype for CALICE has been done in 20042007; the Si. PM’s for it were developed in 2003. At that time HAMAMATSU (MPPC) (which now produce the devices with record parameters) wasn’t manufacturing it at all. This business growing extremely fast 2. And more important. The existing Si. PM characteristics are sufficient and furthermore adequate for our goals Let me illustrate it. This is one of our results – light yield distribution from MIP for all tiles. Looking only on mean value (over all three tile sizes) of the LY = 13. 5 pixels. What it means? Si. PM has 1156 pixels and therefore has limited dynamic range. Having 13. 5 pixels per MIP we can measure energy per cell up to ~ 200 MIP. More efficient detector leads to reduction of this range. Thus, we don’t need higher sensitivity Si. PM - only for given task, of course 9 V. Rusinov 10 -th INTERNATIONAL CONFERENCE ON INSTRUMENTATION FOR COLLIDING BEAM PHYSICS Novosibirsk, March 4, 2008

Noise rate Mean value for Si. PM’s used is equal to 2 MHz, and it looks terrible. But the noise drops fast with threshold increase. random trigger 1 p. e. 2 p. e. Ped. 3 p. e. So, if Threshold=0. 5 MIP noise rate=1. 8 k. HZ It leads to 3 noise events from all 8000 channels for 200 nsec gate and with a such threshold we have 93% efficiency of the whole detector The better detectors could give more flexibility in threshold choice and could add few percent in efficiency. But, nevertheless, characteristics of Si. PM’s from MEPh. I – PULSAR were quite adequate for our goals. And - of course – for some other tasks. 10 V. Rusinov 10 -th INTERNATIONAL CONFERENCE ON INSTRUMENTATION FOR COLLIDING BEAM PHYSICS Novosibirsk, March 4, 2008

Impressions from dealing with Si. PM Advantages • • Small size compact and high granulated detector Low operating voltage Fast Large gain, simple electronic Self-calibration possibility Insensitivity to magnetic field Reliability – problems solved Price (? ) Limitations • Low radiation hardness* • Strong voltage (temperature) dependence** • Limited dynamic range • High noise level In conclusion of this part. It was really a pleasure to work with MEPh. I – PULSAR team: Boris Dolgoshein, Sergey Klemin, Elena Popova and other people, who developed Si. PM’s and produced many thousands of them! Peak resolution up to ~ 1 krad protons, 500 krad e (or gamma), 5× 10 10 fast neutrons/cm 2; recovery for some of detectors; necessary to think separately in each case ** d(MIP)/d. T=-4. 5%/K ; d(MIP)/d. V=7%/V the dependence from only one value! * 11 V. Rusinov 10 -th INTERNATIONAL CONFERENCE ON INSTRUMENTATION FOR COLLIDING BEAM PHYSICS Novosibirsk, March 4, 2008

Our HCAL prototype is working! The unique granularity allows to separate closest showers Reconstruction algorithm: (V. Morgunov) applied to HCAL only. Clusters grouped according to topology and hit amplitude. Separate: EM and HAD shower components + neutrons (= isolated hits) Event with 2 hadrons after reconstruction. Two showers separated in depth are visible 12 V. Rusinov 10 -th INTERNATIONAL CONFERENCE ON INSTRUMENTATION FOR COLLIDING BEAM PHYSICS Novosibirsk, March 4, 2008

Detector unit: scintillating tile+ WLS+ Si. PM gives possibility to construct HCAL. But for scalable prototype we still search other solutions. Example 1: How to make calorimeter with >106 channels? One of the first possible steps is to read out light directly from tile without WLS scintillator Si. PM 2 problems right away: • low light • response non-uniformity glue MC simulation by E. Tarkovsky (ITEP) Result from ITEP proton beam We can equalize the response only by cutting the peak, but the light problem will grow. New detectors are necessary. V. Rusinov 10 -th INTERNATIONAL CONFERENCE ON INSTRUMENTATION FOR COLLIDING BEAM PHYSICS Novosibirsk, March 4, 2008 13

Example 2. Scintillating strip as detector unit -Time measurements. D 1 Strip with WLSF Trigger counters D 2 1. 2 mm Y 11 1 mm BCF 92 Delays t 12=t 1 -t 2, t 1 T=t 1 -t. T, t 2 T=t 2 t. T have been measured 14 V. Rusinov 10 -th INTERNATIONAL CONFERENCE ON INSTRUMENTATION FOR COLLIDING BEAM PHYSICS Novosibirsk, March 4, 2008

Example 3. Scintillating strip as detector unit. - Light Yield and Efficiency 2000 x 25 x 10 2 Si. PM’s mm 3 1000 x 40 x 10 mm 3 coated with Ti. O 2 white paint Ø 1. 2 mm Kuraray Y 11 WLS fiber glued into a groove MRS APD + mirror at opposite end Strip efficiency and noise vs threshold 15 , V. Rusinov 10 -th INTERNATIONAL CONFERENCE ON INSTRUMENTATION FOR COLLIDING BEAM PHYSICS Novosibirsk March 4, 2008

Possible directions and Activities 1. Direct light reading from tile. what do we want from Si. PM Requirements to detector 1. 2. Energy measurement up to hundreds MIP, large dynamic range (>103 pixel), high efficiency in blue light (>20%), low noise (<100 Hz at ½ MIP), larger area, flat packaging. No energy measurement, 102 pixel, small area (1 -1. 5 mm 2), high efficiency in green (>30%), not so strong requirements to noise level. 2. Long scintillating strips with WLS: • • • muon detector veto or trigger wall time (or coordinate) measurements 3. Neutrino detector based on scintillating strips and WLS ( ν + p = n + e+) Neutron detector based on scintillator doped with B 10 and WLS 3. -4. Energy measurement from ½ MIP, 103 pixel, small area (1 -1. 5 mm 2), high efficiency in green (>30%), lowest noise level (to start with low threshold). Gamma detection in liquid Xe 5. 4. 5. No energy, 102 pixel, large area (16, 25 mm 2), sensitivity to UV, any noise One of main impressions from Si. PM – non-universality. New task requires new detectors. 16 V. Rusinov 10 -th INTERNATIONAL CONFERENCE ON INSTRUMENTATION FOR COLLIDING BEAM PHYSICS Novosibirsk, March 4, 2008

It is clearly seen - various detectors are needed MRS APD from CPTA, Moscow 1 mm 2 green MRS with ε=30% 4 mm 2 ------------- 25% 4 mm 2 blue MRS with ε=25% Noise rate~ 2. 5 MHz/mm 2 Efficiency - good for different purposes Noise – not so good yet So, we continue to work with producer, hoping to get better and various detectors The cooperation with Russian producers looks perspective due to easy communication and fast response. Important to have a possibility to order what you really need together with a possibility to buy in a good shop (HAMAMATSU) what they have 17 V. Rusinov 10 -th INTERNATIONAL CONFERENCE ON INSTRUMENTATION FOR COLLIDING BEAM PHYSICS Novosibirsk, March 4, 2008

CONCLUSION • The active layers construction for HCAL prototype was a big and interesting work for our group, the 8000 -channel device was finished last summer • We have obtained an unique experience with more than 10000 Si. PM’s and positive impressions of them • We principally know how to produce HCAL based on unit described (tile – WLS – Si. PM) and we are searching other possibilities • We see further possible applications for such kind of detectors And – thanks to organizers! 18 V. Rusinov 10 -th INTERNATIONAL CONFERENCE ON INSTRUMENTATION FOR COLLIDING BEAM PHYSICS Novosibirsk, March 4, 2008

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