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Basel LNP, a discrete Preamplifier for VPT/T (&APD) readout, Preliminary Datasheet model SP883d
Manual/Datasheet Preamplifier SP883d
Author: Werner Erni
Experimental Particle Physics Group of Prof. Dr. Bernd Krusche
in collaboration with Dr. Irakli Keshelashvili, Michael Steinacher, Universität Basel, CH;
Universität Bochum, D; GSI Darmstadt, D; KVI Groningen, NL
Status: Preliminary Draft
Version 0.1; December 23, 2010/Werner Erni
8; August 3, 2011/Werner Erni Photo: Preamp SP883d soldered to Hamamatsu VPT Main Features of low noise/low power charge preamplifier model SP883d
• Low noise (high resolution) relative to power consumption
• For Vacuum Photo Triodes (VPT), Photo Tetrodes (VPTT) & APD
• Completely analog electronics
• Single ended, AC-coupled 50Ω positive signal output
• Integrated low power HV-Divider(Bleeder/Bias) for up to 1,5kV. Space saving, significant less cables (1 instead of 3)!
• Integrated low & high voltage power supply filter
• Reduced dimensions (length 28mm), short “stamp” format
• Two separate boards (PCB), without PCB-connectors
• Low cost with components of the shelf
• Operation at -25°C, radiation and magnetic fields
• Fast rise time (20ns) for energy & time measurements
• Single range: reduces ADC-channels (cost), power, space
• Driver for signal transmissions integrated (drives 50 Ohm standard coaxial cables)
• Easy operation: Power supplies (LV+HV) in - Signal out SP883d_Datasheet_Manual_Preamp page 1 of 40 Physics Uni Basel, CH-4056 Basel Basel LNP, a discrete Preamplifier for VPT/T (&APD) readout, Preliminary Datasheet model SP883d Table of Contents (F9 to refresh) Manual/Datasheet Preamplifier SP883d
Concept of the Panda Electromagnetic Calorimeter EMC readout
Panda EMC Forward Endcap Proto 192 (red marked)
Family of LNP preamplifiers
a.) Hamamatsu Triode R11375MOD3
b.) Hamamatsu Tetrode R11375MOD
c.) Hamamatsu APD S8664-1010 and S11048 (“rectangular”), datasheet available.............. 7 d.) RIE Tetrode (VPTT)
e.) Hamamatsu Triode R2148 (metal, short)
General remarks for operation
Application Hints for best operation
Comparing noise measurement results
Noise measurement setup
Example (Noise measured with shaper and oscilloscope)
Wiring & Assembling
Diffences between SP883d Prototypes and Serie –Version.
Wiring for series-version:
1. Connecting/wiring of power supply
3. VPT/T connection
4. Assembling VPT/VPTT
5. Adapter-PCB for Dual APD/crystal
Schematic diagram SP883d (for VPT/VPTT)
Differences between the versions of SP883d_PS (VPT, VPTT, …)
Circuit/component function description
Distribution of Power Supplies
HV for Proto192
LV (+/-6V or +8/-2V)
Signal to Noise ratio
Noise vs. Cooling vs. detector capacitance
Rise Time/Timing Information
Crystal & Alveoles
SP883d_Datasheet_Manual_Preamp page 2 of 40 Physics Uni Basel, CH-4056 Basel Basel LNP, a discrete Preamplifier for VPT/T (&APD) readout, Preliminary Datasheet model SP883d Addendum
Distribution of Power consumption
Energy resolution: Comparison of ASIC readout (prototype 16) & LNP readout (Proto60)......... 34 References
Overview LNP Preamplifier “Champ” (Charge amplifier) -Familiy (Evolution Chart)............. 37 Test Setup (SP903c)
The Prototype SP883(c)d
Electronic circuits can be damaged by Electrostatic Discharge, ESD. It is strongly recommended that all devices be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from performance degradation to complete device failure, sudden or while operated.
ESD is produced by walking on floors, through friction on isolating surfaces, shoes, clothes, etc.
Basic methods are not to touch, use conductive ESD-bags to store and grounding strips when handling the device.
Concept of the Panda Electromagnetic Calorimeter EMC readout The Low Noise / Low Power Charge Preamplifier (LNP “Basel”-Preamp) is a discrete charge preamplifier which has an excellent noise performance in combination with low power consumption. It is designed for the readout of Photodetectors for the Panda Electromagnetic Calorimeter (EMC). The Photodetectors (LAAPD, VPT, VPTT) are attached to the end face of the lead tungstate scintillating crystals (PWO-II) 3 which have a typical geometry of (200 x 20 x 20) mm. In comparison to a photomultiplier, theses photodetectors are working better in a strong magnetic field. Further, the vacuumphotodetectors as Vacuum-Photo-Triode (VPT) and the Vacuum-Photo-Tetrode (VPTT) are better for high radiation which occurs in the center of the forward endcap than the semiconductor device LAAPD. Therefore the barrel and the backward endcap of the EMC is equipped totally with LAAPDs and the forward endcap works with VPT/T’s and LAAPD’s dependent of the region. These devices act as photo detectors converting the scintillating light to an electrical charge. Then, the LNP-Preamp linearly converts the charge signal to a positive voltage pulse which is transmitted via a 50 Ohm line to the subsequent electronics.
Since the complete EMC including the preamplifiers will be cooled to -25° (to increase the light-yiel d of C the PWO-II crystals), the power dissipation of the preamplifier has to be minimized. Low power dissipation leads to a smaller cooling unit and thinner cooling tubes; it also helps to achieve a uniform temperature distribution over the length of the crystals. The LNP-Preamp has a quiescent power consumption of 45 mW. The power dissipation is dependent on the event rate and the photon energy; at very high rates combined with the maximum photon energy, the power consumption is increased up to 90 mW.
SP883d_Datasheet_Manual_Preamp page 3 of 40 Physics Uni Basel, CH-4056 Basel Basel LNP, a discrete Preamplifier for VPT/T (&APD) readout, Preliminary Datasheet model SP883d
This LNP Preamplifier was built for applications where low noise and low power consumption is essential, as specially for the PbWO-crystal read-out of Panda Calorimeter at GSI, Darmstadt.
Other preamps with lower noise are on the market but with higher power consumption.
The model SP883d is the latest version of a family of preamps originally designed for APD with a capacitiy of up to 500pF (f.e. two paralleled Hamamatsu S8664-1010 or S11048).
The output is a positive low noise single ended 50Ω-signal, useable for energy and timing measurement. Therefore no shaping is on board, this must be done externally. The shaping time for energy measurement defines then the noise. While the signal/noise ratio with VPT is comparable to those with APD, the absolute signal and noise level is much lower and therefore the sensitivity is higher and all activity to prevent from noise must be even better.
The influence of the noise from the preamplifier is proportionally higher in relativity to the vacuum photodetector with lower capacitance.
A low power HV-divider circuit for up to 1.5kV is also implemented. This low power circuit is a new method, because manufacturers of tubes recommends higher power consuming bleeder circuits. Hence it was possible to implement the divider on the preamp itself in the cooled - and therefore power loss critical sector- of the detector. This innovative concept reduces not only problematic temperature gradients to the photodetector and the crystals, but also the amount of HV-cables and therefore space and cooling losses.
To implement the additional HV-circuit on the reduced area, the preamp was split into two PCB’s. In addition, it prevents from leakage currents to the input of the amplifier stage. Each type of photodetector needs his very own typical divider-circuit which is placed on one of the two boards. As tradeoff this results in slightly more noise.
A precise power-on-point HV-generation onboard (“active base”) is not foreseen due to additional heat generation and the magnetic fields at that point. The use of unshielded magnetic components as inductors for power conversion and filtering is problematic.
The leave out of connectors reduces material, volume, costs and weight and increases reliability. The preamp is connected to the next signal chain stage (either a shaper or a distribution panel) via short wires/cables/PCB and the connection to the photodetectors is also short.
The preamplifier is made of commercial standard low cost components of the shelf.
An adapted version for use with APD’s is also available. The appropriate HV-circuit (filter) which works also as an interconnection to the APD’s is designed for two preamps/crystal of either type SP883d (18x28mm) or SP883a02 (18x48mm).
This version has reduced series filter resistance to reduce the voltage drop at high rates.
SP883d_Datasheet_Manual_Preamp page 4 of 40 Physics Uni Basel, CH-4056 Basel Basel LNP, a discrete Preamplifier for VPT/T (&APD) readout, Preliminary Datasheet model SP883d Panda EMC Barrel Proto60 (Picture Tobias Eissner) Uni Basel, IPN Orsay, Uni Giessen, etc.
Panda EMC Forward Endcap Proto 192 (red marked) Uni Basel, Uni Bochum, etc.
SP883d_Datasheet_Manual_Preamp page 5 of 40 Physics Uni Basel, CH-4056 Basel Basel LNP, a discrete Preamplifier for VPT/T (&APD) readout, Preliminary Datasheet model SP883d Main Challenges
• Low noise at low power
• Signal transmission/output voltage/dynamic range
• Low overall cost/easy operation
• Energy and time measurement (no onboard-shaper)
• Max. Rate/pile-up
• Low power loss HV bleeder for operation in cooled areas
• Flexible design for different photodetectors APD/VPT/VPTT Family of LNP preamplifiers Since the APD-Version of the preamplifier was developped years ago and many measurements and tests were performed with it, refer to the datasheet SP883a02 or the TDR 2008 for specific data for use with APD’s. The actual version SP883d and the new types of vacuumphotodetectors were developed in 2010.
Therefore they are still in test phase. Below an overview is shown:
Note: type number key, Example SP883d01_APD:
SP Schematic Plan 883 Projectnumber Electronics Lab Physics Basel for the Panda EMC Preamp d Model/Type/Version 01 Revision 1 _APD variante/adaption
SP883d_Datasheet_Manual_Preamp page 6 of 40 Physics Uni Basel, CH-4056 Basel Basel LNP, a discrete Preamplifier for VPT/T (&APD) readout, Preliminary Datasheet model SP883d Photodetectors a.) Hamamatsu Triode R11375MOD3 b.) Hamamatsu Tetrode R11375MOD
c.) Hamamatsu APD S8664-1010 and S11048 (“rectangular”), datasheet available d.) RIE Tetrode (VPTT) Thanks to Michael Leyhe, RUB, 29.1.2010 VPTT (RIE) with silicone Isolation and protection VPTT (RIE) without silicone potting e.) Hamamatsu Triode R2148 (metal, short)
SP883d_Datasheet_Manual_Preamp page 7 of 40 Physics Uni Basel, CH-4056 Basel Basel LNP, a discrete Preamplifier for VPT/T (&APD) readout, Preliminary Datasheet model SP883d
*Measured on a modified single board prototype, by Michael Steinacher, 2008, Uni Basel SP883d_Datasheet_Manual_Preamp page 8 of 40 Physics Uni Basel, CH-4056 Basel Basel LNP, a discrete Preamplifier for VPT/T (&APD) readout, Preliminary Datasheet model SP883d General remarks for operation This Preamplifier was designed to work directly with the VPT or VPTT from RIE or Hamamatsu, but • can also be adopted for other detectors and mechanical designs.
To save space, cables are soldered directly onto the PCB.
• The use of an AC coupled device has many advantages, as to prevent common mode GND-level • problems and crosstalk, but might also cause problems, because the shift of the signal baseline on the trigger branch side at high and fast changing rates. To prevent this, the signal output is terminated with 50Ω. The transmission line (PCB/shielded flat or coaxial cable) and the input of the following shaping amplifier must have also 50Ω impedance.
The output signal is about 0.5V/pC when terminated with 50Ω (1V/pC unterminated).
• The peak output is an optimised voltage for ADC-Inputs (2V).
• The Preamp has one single ended output and is therefore optimized for ADC‘s with 2.5V Inputs (f.e.
• Wiener, Struck, CAEN, etc.).
The signal must be measured relative to its proper ground, as it is widely used in critical signal • processing. Baseline restoring with shaper. Ref.: E. Kowalski “Nuclear Electronics”, Springer-Verlag, p.106ff, 163 Prevent the preamp from electrostatic discharge (ESD), specially if the input is open (no VPT).
• Do not touch the boards because of creepage currents through salts from hands..
• Floating power supply +/-6V, f.e. from a NIM-Chassis, the Basel model SP903b or a laboratory power • supply (alternatively +/-5V).
Floating HV low noise power supply (often a linear regulated HV power supply as the Fluke 341A).
• The filter-circuit of the preamplifier is designed for positive HV, Max. voltage is +1500VDC • The voltage divider is placed on the preamplifier with only one HV-wire to save space and thermal • conductivity.