The PSD upgrade performance

• Front-End-Electronics• MAPD HV system• Temperature stabilization • MAPD gain monitoring system• Slow control• Readout –present and future.

- First estimation of the PSD capability for reaction plane measurements at NA61.

A.Ivashkin on behalf of INR group

1NA61/SHINE collaboration meeting, CERN 22-26 September, 2014

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PSD – Projectile Spectator Detector

Precise measurement of the energyof projectile spectators.•Centrality selection (on trigger level)• Measurement of event-by-event fluctuations (to reduce Npart

fluctuations)• Reconstruction of the reaction plane

Compensating calorimeter•Pb/scintillator (4/1) 60 sandwiches in one module•Modules 10 x 10 x 120 cm3 – central part• Modules 20 x 20 x 120 cm3- outer part• 10 longitudinal sections with 10 MAPDs readout

PSD in 2011

PSD modules in 2011 Be-run

1.The PSD cooling system was not working properly (air flow from basement).

1. The temperature control system is not working properly

2. No feed back to MAPD voltage.

3. Long term stability of MAPD gains was not monitored.

4. Raise time of PSD trigger signal was slow – problem with the time-amplitude walk and signal delay in trigger box.

5. Electronics noise was rather small but comparable with MIPs signal. Muon calibration was rather challenging.

Necessity of PSD upgrade.

Ebeam =30AGeV

Energy in PSD

Temperature

MAPD gain ~4 %/0C

PSD was constructed with the minimum functionality that lead to some problems with PSD have been found during Be-runs:

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The PSD trigger signal in 2011-2013.

60 ns300 ns

MAPD signal M~5x104

integrated signal M~107 ADC signal

2011-2013 Be runs:

the PSD trigger signal comes after integrators with rise time ~60 ns: rather slow and large time-amplitude walk. Needs careful adjustment for each beam energy.

In 2014 - :….

trigger signal after MAPD – fast signal, no problem with time walk and delay.

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Strategy of the PSD upgrade1. New cooling system with temperature control system.

2. New HV control (readout of real voltages).

3. Monitoring system for the MAPD gains (LED stabilized source).

4. New fast amplifiers for the PSD signals and trigger.

5. Compatibility with new DRS4 readout system.

5. Compatibility with existing readout (old mother boards).

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Summer 2013

All PSD electronics has been dismounted

June 2014

The PSD after upgrade

New FEE for PSD

10 Analog signals +trigger (adder)

MAPDs

Al-plate+Armaflex

LED source

HV channels

SC connector

• All 10 MAPDs at Al-plate for cooling.• 10 fast amplifiers and HV power sources individually for each photodiode.• Two (high/low gain) outputs in each amplifier.• Fast analog adder in each module for PSD trigger.• Stabilized LED source for MAPD gain monitoring.

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PELTIER COOLER

New scheme of MAPDs cooling and temperature stabilization with Peltier element.

Heat sink

Temperature sensor

Copper heat sink

Alplate

External TECcontroller

PSD module electronics

Compressed air

Ts -sink temperature sensorTo -object temperature seensor

To

Ts

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Fully assembled cooling system, FEE, HV and control system for one module.

TEC-controller

Air-inlet

SinkPeltier

FEE+MAPD

Copper rod

In total we have 44 +3 (spares) sets of electronics.

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Controller for slow control system

• Originally developed for COMPASS ECAL

• Can control up to 127 devices (modules).

• Control the MAPD HV settings.• Control the gain monitoring system

(stabilized LED sources).• Connection with external computer:

USB-2.0 or RS-232. Controller for SC

New HV distribution system

• Extremely low power consumption.• HV stability – 0.01%.• One external power supply ~12 V.• Permanent check of HV values. There is feedback to HV!• Already tested for a few years!

Developer - HVSys Co., Dubna.

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PSD readout PC

HVSys HVSys HVSys . . . HVSys

flat cable

TEC TEC TEC TEC

RS485 network (twisted pair)

HV & LED controlbox

USB to RS485Converter

LAN

USB

PSD slow control for temperature, gain, and MAPD HV.

HVSys, Dubna

USB to RS485Converter 2 RS485 networks X 22 channels each

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Cooling system long term (a few days) tests.

New MAPDs cooling system based on the Peltier elements provides stable (within 0.1 0C) temperature in each module.

Ambient temperature

Module temperature (MAPD Al-plate)

FEE - noise source: TEC-controller for Peltier elements.

TEC OFF TEC ON

one event one event

TEC OFF TEC ON

one event one event

effect on pedestal

effect on MIP-like signal

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noise with constant periodTime bins

Time binsTime bins

Time bins

Noise effect at pedestal and MIP-like signal.

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pedestalTEC OFF

Time bins

pedestalTEC ON

Time bins

100 “ticks”

pedestal calculation

signal calculation

Time bins

Due to the periodic structure of noise the effect is minimal, because the noise is the same in pedestal and signal regions.

MIP-likeMIP-like

MAPDs gain monitoring system.

Light amplitude is controlled by PIN-diode inside with very low temperature dependence.

Control of MAPD gain at ~1% level.

Based on stabilized LED source.

LED amplitude vs time LED amplitude distribution

(~30 hours).

~1%

Small module

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Now fast trigger signal is avaialble.

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Signal shape after adder. Rise time ~10 ns

No time walk! No extra delay of trigger signals!

Present scheme: MAPDFastAmp.G=30

Adder

Calibration with cosmic muons.

• Trigger – sum of adder signals from all modules.

• At least one section in PSD module must be fired.

• The spectrum contains the pedestals mainly.

Small module Large module

ADC [ch] ADC [ch]

Dedicated event selection is needed! 16

Matching with readout electronics (present and future variants).

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Shape and amplitude of MAPD signal after amplifier are PMT like ones. Easy to adapt to any readout scheme.

Two amplifiers increase the dynamical range of detected energies. (especially important for heavy ion program)

Present variant : MAPDFastAmp.G=30

Signal adapter

Slow amp.-integrator

CB

Future (DRS4) variant :

MAPDFastAmp.G=30

DRS

FastAmp.G=120

DRS

(for high energy deposition)

(for low energy deposition+ muon calibration)

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Future DRS readout

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Number of DRS channels:

• 440 MAPDs in PSD. 440x2 (high/low gain) amplified signals are available.

• 440x2=880 DRS readout channels for individual MAPD readout.

• For the pile-up identification the adder signal must be in the time window 8 ms. A 6 groups of 8 modules might be digitized in this window.

~ 6 DRS channels with extended time window are required.

Cables, connectors, patch-panel?

PSD and flow measurements.

Can it be used for the reaction plane reconstruction?

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First estimation on reaction plane resolution measured with the PSD at NA61

Simulations have been done for

- Ar+Sc at 7 energies 12, 18, 29, 39, 75 and 149 AGeV - Xe+La@39 AGeV

- Au+Au@10 and 35 AGeV for NA61 and compared with CBM geometries

Reaction plane angle calculations were done in 5 centrality bins: b: 0-2, 2-4, 4-6, 6-8, >8

Corrections of reaction plane angles due to magnetic field and flattering procedure were applied

10000 events for were generated with Shield code and transported

(all particles) from the target to PSD via Geant4.

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Au35Au, NA61, 8cm, 17m Au35Au, CBM, cbmroot, hole6cm, 6.5cm, 15m

Xe+La@39 AGeV

Ar+Sc@12, 18, 29, 39, 75 and 149 AGeV - reaction plane resolution vs b - 80 – 100 degrees.

Reaction plane resolution for different systems.

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Reaction plane resolution at CBM (FAIR)

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PSD

Au-beam energy 2-30 GeV.Magnet field.

Reaction plane resolution is consistent with NA61

MC numbers.

Conclusions:

1) New FEE for PSD is installed and tested.

2) The PSD slow control and temperature control systems have been tested.

PSD is ready for muon calibration at beam in October 2014

3) First simulation of reaction plane determination by the PSD was done.

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To do• PSD slow control is to be implemented in NA61 DCS.

• Readout by SC of the temperature in PSD modules creates picked-up noise in MAPD amplifiers during readout (a few seconds). Would be nice to synchronize this readout with the spill structure.

• MAPD gain monitoring system is working in stand-alone mode when PSD is triggered by LED signals. Is it possible to incorporate this trigger to common DAQ?

Thank You

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