R&D of Calorimeter using Strip/Block Scintillator with SiPM E.P. Jacosalem, S. Iba, N. Nakajima, H. Ono, A.L. Sanchez & H. Miyata Niigata University ILC Detector Workshop KEK Kenkyu Honkan Lecture Hall March 3-5, 2005

Contents Introduction Scintillator systematic study (by E.P. Jacosalem) Compare the pulse height vs surface covering Compare the strip type scintillator length, block type scintillator thickness and WLS fiber length with pulse height SiPM study (by IBA Sayaka) Laser signal in oscilloscope Bias distribution Position distribution Summary

Introduction Needs fine segmentation CAL Small scintillator -> fine segmentation Small scintillator We plan many types of scintillator Compare of some type of surface covering (Al evaporation, White Paint etc.) SiPM Using SiPM for readout Developed in Russia Compact SiPM measurement using Laser system Measurement of SiPM details Bias distribution Position distribution Future Plan

Scintillator study Sensor : Strip type scintillator ( length: 4,8,12cm) Block type scintillator (thickness: 2mm, 5mm) Trigger : Scintillator (about 1cmx8cmx5mm ) with PMT directly connected Source : 90Sr (beta-ray) WLS fiber diameter: 1.0mm ; (length 13cm, 22cm) PMT (sensor) : 16 Ch MAPMT H , HV : -950V PMT (trigger) : H3164, HV : -900V Setup Source point location

Compare of Surface covering Al and Au evaporation  total reflection of photon White paint or Teflon wrapped  diffuse reflection Black tape  absorption We compare each type using ADC system Al evaporation White paint Au (Gold) evaporation Black tape

Pulse Height vs Surface Covering Use 10x40x2mm Strip scintillator Compare of scintillator surface covering Black tape, White paint, Teflon wrapped, White+Teflon, Al and Gold evaporation WLS fiber length : 22cm White paint +Teflon is the best surface covering Teflon wrapping makes flat surface Legend: Al - Aluminum Au - Gold BT - Black Tape T -Teflon WP – White Paint WPT – White Paint with Teflon

PH vs Strip Scintillator Length of Different WLS fiber length Compare of charge for strip scintillator length Compare of WLS fiber length, 13 c m and 22cm) Strip type scintillator length VS pulse height length Signal Pulse Height signal pedestal

PH vs Block Type Scintillator Thickness Compare the PH vs thickness 5mm thick scintillator had greater PH

SiPM study From Russia Micro Avalanche Photo Diode (APD) Each pixel in Geiger mode 34x34=1156 pixels in small area (1.2mmx1.2mm) High Gain : ~10 6 Operational at low voltage (about 60~70V) Wire Bonding 2mm 34*34 =1156pixels 1.2mm K A

Two types of SiPM Both pixel are same, but arrange of pixel is different This time, we use Type B Pixel Size : about 30umx30um Type A Type B about 30um

Setup Circuit plan is from Russia Sensor bias : 60-70V Logic Laser : YAG(Nd 3+ Y 3 Al 5 O 12 ) Trigger : from Laser system Charge : 20mJ/cm 2 for 1064nm 10mJ/cm 2 for 532nm Use filter -> down Output Circuit The Laser System

Signal of laser(1064nm, 532nm) 532nm signal is smaller than 1064nm 532nm result has many noise than 1064nm Less noise is necessary for ADC measurement 1064nm 65.0V 532nm 67.0V 532nm 66.0V 20mV 10mV 50nsec

Sensor bias distribution (1064nm) Laser wave length : 1064nm Above 67.5V, it has saturation Laser hitting area (about 6x6 pixel more)

Noise level(1064nm) Noise level Relationship between Pedestal sigma and Sensor bias S/N rate Relationship between S/N rate and Sensor bias S/N rate is dividing Pulse Height by Pedestal sigma sigma PedestalSignal S/N rate Noise level

Sensor bias distribution (532nm) In 532nm case, no saturation Above 68.0V, there are much noise Below 65.5V, signal rate is very low

Noise level(532nm) The same analysis as to 1064nm bias distribution Noise level increases as bias increases Best S/N rate range is about 65.5V – 67.0V Best operational bias voltage: 66.5V Noise levelS/N rate

Position Distribution Laser wave length : 1064nm Sensor bias : 66.5V 49points (7x7points) were measured Laser output fluctuation range : ~10% Edge parts is lower Pulse Height Laser hitting area ( more than 1 pixel)

Problem of Laser intrinsic noise When we use Laser system, there is Laser intrinsic noise on Sensor signal At big signal, this noise isn’t problem but at small signal like above figure it is big problem Anyone can’t remove this noise in our laboratory before Adjust gate width?? 2mV 5mV Laser intrinsic noise Laser area : 1~9 pixel Expansion

Future Plan: Connection between Scintillator and SiPM Way of connection Scintillator -> WLS fiber ->SiPM Type of scintillator Strip(10x2mm with length : 4,8,12,16cm) Block (10x10mm with thickness : 2, 4, 5, 6, 8 and 10mm) Tile (40x40x2mm) Surface : Al evaporation, White Paint, Teflon wrapped, etc WLS fiber : diameter 1mm, 1.6mm Use best conditioned scintillator Strip typeBlock type

Summary Scintillator study White Paint +Teflon is the best surface covering Longer strip-type with shorter WLS fiber has greater PH 5mm thick block-type scintillator has greater PH by compared to 2mm thick SiPM study Got signal Best operation voltage : about 66.5V Highest PH at the center and lowest at the corners and edge.

Future plan Connect the Scintillator and SiPM Presentation at LCWS2005 (Miyata-sensei) and 2005spring JPS (Iba)