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Test Setup for PHOBOS Hybrid/Module Testing at MIT Pradeep Sarin 31 July 98.

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Presentation on theme: "Test Setup for PHOBOS Hybrid/Module Testing at MIT Pradeep Sarin 31 July 98."— Presentation transcript:

1 Test Setup for PHOBOS Hybrid/Module Testing at MIT Pradeep Sarin 31 July 98

2 Test Setup Module (Type 1) Repeater Card Function: a) Distribute V det ; ±6V to V ss and V dd b) Control current and voltage params. c) Route control signals from PC to Hybrid. Transition Card Function: a) Simple re-routing of wires b) Jumpers for temperature sensor LabVIEW PC Function: Logic : Use on-board logic or External NIM logic to time and route TRIG, HOLD, CLK, TESTP etc signals. National Instruments SCB Box 26 pin cable 50 pin cable 20 pin cable Computer Cable Power Supply V det Power Supply +6V Power Supply -6V Sr-90 Src Scintillator NIM Logic Trigger

3 Calibration Algorithm for LabVIEW Switch Test Mode OFF Take ~300 Pedestal Events. Calculate avg pedestal for each channel  Zero input signal, digitize output Switch Test Mode ON Send Test Pulse into VA chip with level=V cal Send HOLD signal after T peak ~ (1.2 to 2.0  s) Acquire and Digitize Analog Output of VA chip Do “Signal Conditioning” Increment V cal

4 Calibration Timing Test Mode ON OFF Test Pulse HOLD VA Analog O/P TRIG CLK (25 kHz) (Random Trigger) Into PC/Logic From PC From PC/Logic To ADC 20  s 10  s (Not to Scale!) Precisely adjustable T peak  s  s PED Chan 0PED Chan 2 PED Chan 1 Digitize VA Reset 1 3n+12 Trigger Disabled

5 Source Test Algorithm for LabVIEW Take ~300 Pedestal Events. Calculate avg pedestal for each channel  Zero input signal, digitize output Trigger on Scintillator Signal Send HOLD signal after T peak ~ (1.2 to 2.0  s) Acquire and Digitize Analog Output of VA chip Do “Signal Conditioning” Move Radiation Source?

6 Source Test Timing (Not to Scale!) VA Analog O/P Scintillator TRIG CLK Into PC/Logic From PC/Logic To ADC Precisely adjustable T peak  s Digitize N Channels VA Reset 13N+12 HOLD External Trigger Disabled ADC_Start TRIG to PC SHIFT_IN to VA Example Signal held in any one channel LabVIEW VI Can be Zero

7 “Signal Conditioning - 1” Pedestal Subtraction pedestal for each channel is average of ~300 pedestal events measured initially, before the test begins

8 “Signal Conditioning - 2” Common Mode Noise Correction Calculate Avg signal in all Empty channels, leaving out the channels that have a real hit  SIG CMN Subtract SIG CMN from signal in each channel SIG CMN

9 “Signal Conditioning - 3” Pedestal Drift Correction Has been noticed in testing of Type 1 modules (caveat - no handle on temperature stability) 0127 What may happen: Pedestal Subtraction and CMN correction gives noisier signals - Real pedestals are different from measured pedestals

10 “Signal Conditioning - 3 (contd)” Currently to correct for pedestal drift we can do: Signal (ADC) distribution (after Pedestal subtraction and CMN) Gaussian Noise Landau Signal 0 The Zero mean of the Gaussian noise drifts because of drift in pedestals Add the value of the mean (weighted by a factor) to each channel’s pedestal every ~50 events

11 Calibration Tests 1. Gain per Channel 2. Electronically dead channels 3. Pedestals per channel Source Tests 1. Pedestals per channel 2. Signal/Noise Ratio for Sr-90 source 3. Signal Distribution 4. Hit profile in detector 5. Noise v/s channel with and without CMN correction Can’t do yet : Interrupted trace lines, but ideas... Capabilities Data is automatically written to ORACLE database


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