FAST ComTec CSPA10 Manuale utente

CSPA10 … 13

Charge Sensitive Preamplifier

User Manual

Grünwalder Weg 28a, -82041 Oberhaching

Germany

Version 1.05, July 15, 2021

F ComTec Gmb 1

Warranty

Equipment manufactured by FAST ComTec GmbH is warranteed against defects in materials and

workmanship for a period of twelve months from date of shipment, provided that the equipment has been

used in a proper manner as detailed in the instructions manuals. uring the warranty period, repairs or

replacement will be made at FAST ComTec’s option on a return to factory basis. The transportation cost,

including insurance to FAST ComTec is the responsibility of the Costumer except for defects discovered

within 30 days after receipt of equipment where shipping expense will be paid by FAST ComTec.

Copyright Information

This manual contains proprietary information; no part of it may be reproduced by any means without prior

written permission of FAST ComTec, Grünwalder Weg 28a, -82041 Oberhaching, Germany.

Tel: +49 89 665180-0, FAX: +49 89 66518040

mail: [email protected]

The information in this manual describes the hardware and the software as accurately as possible, but is

subject to change without notice.

2F ComTec Gmb

CSPA1X_20210623 Page 1FAST ComTec GmbH, Grünwalder Weg 2 a, 2041 Oberhaching, phone: 49-(0) 9 6651 0 -0, fax: 49-(0) 9 6651 0 40, http://www.fastcomtec.com

Description

FAST ComTec’s CSPA10...13 is a single channel charge

sensitive preamplifier module intended for use with various

types of radiation detectors including semiconductor

detectors (e.g. CdTe and CZT), p-i-n photodiodes,

avalanche photodiodes (APDs), and various gas-based

detectors.

The CSPA10 is one of a series of four charge sensitive

preamplifiers offered by FAST ComTec, which differ from

each other most notably by their gain. A guide to selecting

the best charge sensitive preamplifier for your application

can be found at our web site: http://www.fastcomtec.com.

The CSPA1X is a successor model of CSP1X, with easier

classic power supply. Other improvements include

integrated protection circuits and better variability.

Equivalent circuit diagram

Figure 2 shows a simplified equivalent circuit diagram of the

CSPA10, which is a two stage amplifier. The first stage is

high gain, and the second stage is low gain with an

emphasis on supplying sufficient output current to drive a

terminated coaxial cable. Rf (100 MΩ) and Cf (1.4 pF) are

the feedback resistor and capacitor respectively (tdecay=

140μs). The feedback values for the other models are:

Rf =10 MΩ and Cf =15 pF, tdecay= 150μs (CSPA11),

Rf =6 0 kΩ and Cf =75 pF, tdecay= 50μs (CSPA12),

Rf =6 kΩ and Cf =750 pF, tdecay= 50μs (CSPA13).

Theory of operation

Charge sensitive preamplifiers are used when radiation is

detected as a series of pulses, resulting in brief bursts of

current flowing into or out of the preamplifier input.

Depending on the type of detector, this burst of current may

be very brief (<1 ns) or as long as a few μs. For an

idealized detection current pulse taking the form of a delta

function, the detected charge (time integral of the input

current) will ideally take the form of a step function.

The output waveform of an actual charge sensitive

preamplifier will of course have a non-zero rise time: for the

CSPA10 this figure is approximately 7 ns. Furthermore,

capacitance at the preamplifier input (i.e. detector

capacitance) will further slow the rise time at a rate of

0.4 ns / pF. Keep in mind the output rise time will also be

limited by the speed of the detector. For example, the

detection current pulse from a CsI(Tl)/photodiode

scintillation detector has a duration of approximately a

couple μs, so the expected rise time of the charge sensitive

preamplifier output will be at least that long.

The output waveform of the CSP10 using a capacitively

coupled fast square wave pulser at the input is shown below

to the left. At long time domains, the output decays due to

the discharge of the feedback capacitor through the

feedback resistor, with an RC time constant of 140 μs. This

decay of the output waveform is also shown below, to the

right.

CSPA1X charge sensitive preamplifier

CSPA1X_20210623 Page 2FAST ComTec GmbH, Grünwalder Weg 2 a, 2041 Oberhaching, phone: 49-(0) 9 6651 0 -0, fax: 49-(0) 9 6651 0 40, http://www.fastcomtec.com

CSPA1X charge sensitive preamplifier

Specification

Preamplification channels: 1

Equivalent noise charge (ENC)*:

ENC MS: 200 electrons, 0.03 femtoCoul.

Equivalent noise in silicon: 1.7 keV (FWHM)

Equivalent noise in CdZnTe: 2.4 keV (FWHM)

ENC slope: 4 electrons RMS pF

Gain: see table 1

ise time**: 7 ns (see table 1)

Decay time constant: 140 μs (150 μs, 50 μs, 50 μs resp.)

Unsaturated output swing: -3 to +3 volts

Maximum charge detectable per event: (see table 1)

Power supply voltage (Vs): +12 volts nominal

Power supply current: < 30 mA

Power dissipation: < 400 mW

Operating temperature: -40 to +85°C

Output offset: +0.2 to -0.2 volts

Output impedance: 1 or 50 ohms, set by jumper

Physical: Net weight: 195 g (320 g including power supply)

Size without connectors: 113 mm x 70 mm x 24 mm

Size with connectors: 153 mm x 70 mm x 24 mm

* Measured with input unconnected, using Gaussian

shaping amplifier with time constant =1 μs. With a detector

attached to the input, noise from the detector capacitance,

leakage current, and dielectric losses will add to this figure.

** Pulse rise time (defined as the time to attain 90% of maximum

value) has a linear relationship with input capacitance.

Value cited in the table assumes zero added input capacitance.

Tocalculate pulse rise time for practical situations,

use the equation: tr =0.4 Cd + 7 ns, where tr is the pulse rise

time in ns, and Cd is the added capacitance (e.g. detector

capacitance) in pF.

Keep in mind that others factors within the detection system

may further limit this value.

Table 1: Sensitivity Versions

Preamp model Gain (mV

/picoCoulomb)

Max. detect.

Pulse (e-)

equiv. noise in

silicon keV

( WHM)

CSPA10 1400 107 1.7 keV

CSPA11 150 108 6.0 keV

CSPA12 15 109 65 keV

CSPA13 1.5 1010 230 keV

Table 2: model specifications (noise, risetime)

Preamp model noise (ENC)

e- (RMS)*

noise (ENC)

slope e- /p

rise time

(Cd=0p )

rise time slope

CSPA10 200 e- 4 e- /p 7 ns 0.4 ns/p

CSPA11 630 e- 3.7 e- /p 3 ns 0.25 ns/p

CSPA12 6,800 e- 28 e- /p 6 ns 0.25 ns/p

CSPA13 24,000 e- 27 e- /p 20 ns 0.25 ns/p

Table 3: input / High voltage connectors

model Input Connectors input / HV

CSPA1X-2S 2 kV / 10 n SHV / SHV

CSPA1X-4S 4 kV / 4.7 n SHV / SHV

CSPA1X-1B 1 kV / 10 n BNC / BNC

CSPA1X-1BS 1 kV / 10 n BNC / SHV

Table 4: ordering information

Model No. Description Order No.

CSPA10-2S Charge-sensitive preamp, SHV, 2kV/10n , 1.4 V/pC CSPA102S

CSPA11-2S Charge-sensitive preamp, SHV, 2 kV/10 n , 150 mV/pC CSPA112S

CSPA12-2S Charge-sensitive preamp, SHV, 2kV/10n , 15 mV/pC CSPA122S

CSPA13-2S Charge-sensitive preamp, SHV, 2 kV/10 n , 1.5 mV/pC CSPA132S

CSPA10-4S Charge-sensitive preamp, SHV, 4kV/4.7n , 1.4 V/pC CSPA104S

CSPA11-4S Charge-sensitive preamp, SHV, 4 kV/10 n , 150 mV/pC CSPA114S

CSPA12-4S Charge-sensitive preamp, SHV, 4kV/4.7n , 15 mV/pC CSPA124S

CSPA13-4S Charge-sensitive preamp, SHV, 4 kV/10 n , 1.5 mV/pC CSPA134S

CSPA10-1B Charge-sensitive preamp, BNC, 1 kV/10 n , 1.4 V/pC CSPA101B

CSPA11-1B Charge-sensitive preamp, BNC, 1 kV/10 n , 150 mV/pC CSPA111B

CSPA12-1B Charge-sensitive preamp, BNC, 1 kV/10 n , 15 mV/pC CSPA121B

CSPA13-1B Charge-sensitive preamp, BNC, 1 kV/10 n , 1.5 mV/pC CSPA131B

CSPA10-1BS Charge-sensitive preamp, BNC/SHV, 1kV/10n ,1.4 V/pC CSPA101BS

CSPA11-1BS Charge-sensitive preamp, BNC/SHV,1kV/10n ,150mV/pC CSPA111BS

CSPA12-1BS Charge-sensitive preamp, BNC/SHV, 1 kV/10n ,15mV/pC CSPA121BS

CSPA13-1BS Charge-sensitive preamp, BNC/SHV, 1kV/10n ,1.5mV/pC CSPA131BS

Front view:

Input Test in

Back view:

Power Supply Output HV input

Table of Contents

1 Introduction............................................................................................................................................... 6

2 Specifications............................................................................................................................................ 8

2.1 Inputs................................................................................................................................................ 8

2.2 Outputs............................................................................................................................................. 8

2.3 Performance..................................................................................................................................... 8

2.4 Connector types and cables............................................................................................................. 9

2.5 Power............................................................................................................................................... 9

2.6 Physicals.......................................................................................................................................... 9

3 Controls and Connectors........................................................................................................................ 10

3.1 General........................................................................................................................................... 10

3.2 Front Panel / Rear Panel................................................................................................................ 10

4 Installation............................................................................................................................................... 11

4.1 Noise Consideration........................................................................................................................ 11

4.2 etector Bias.................................................................................................................................. 11

5 Operating Instructions............................................................................................................................. 12

5.1 General........................................................................................................................................... 12

5.2 Test Input........................................................................................................................................ 12

5.3 Initial Setup..................................................................................................................................... 12

5.4 Initial Checkout............................................................................................................................... 12

5.5 Protection Circuit............................................................................................................................ 13

5.6 Common Operating Problems........................................................................................................ 13

6 Theory of Operation................................................................................................................................ 15

6.1 Functional escription.................................................................................................................... 15

6.2 etailed Circuit escription............................................................................................................. 15

7 Jumper setting & opening of the case................................................................................................. 17

8 Appendix................................................................................................................................................. 18

8.1 etailed Schematic of the CSPA10…13.........................................................................................18

8.2 Personal Notes............................................................................................................................... 19

F ComTec Gmb 3

Table of Figures

Fig. 1.1: Functional Schematic diagram....................................................................................................... 7

Fig. 3.1: Front- and Rear panel.................................................................................................................. 10

Fig. 6.1: Simplified circuit diagram............................................................................................................. 16

Fig. 7.1: CSPA1X board with jumpers........................................................................................................ 17

Fig. 7.2: CSPA1X board with connectors................................................................................................... 17

Fig. 8.1: etailed circuit diagram of CSPA1X.............................................................................................18

4F ComTec Gmb

WARNINGS

The input of the CSPA1X is very sensitive. Never connect the detector when the high voltage is

applied. Increase or decrease the high voltage only at a very slow rate. Observe the output of

the CSPA1X during bias voltage change with an oscilloscope. Do not allow the output to

saturate during change of high voltage.

F ComTec Gmb 5

Introduction

1 Introduction

FAST ComTec’s CSPA10...13 is a single channel charge sensitive preamplifier module intended for use

with various types of radiation detectors including semiconductor detectors (e.g. Si, CdTe and CZT), P-I-N

photodiodes, avalanche photodiodes (AP s), and various gas-based detectors. The CSPA10...13 is one

of a series of four charge sensitive preamplifiers offered by FAST ComTec, which differ from each other

most notably by their gain. A guide to selecting the best charge sensitive preamplifier for your application

can be found on the next page or at our web site: http://www.fastcomtec.com. As with all FAST ComTec’s

preamplifier modules, the CSPA10...13 is housed in a small shielded metal case with a input for plug-in

power supply.

CSPA1x is a successor model of CSP1x, which includes easier supply with classic plug-in power supply.

Other improvements include integrated protection circuit and better variability.

The FAST ComTec Model CSPA10...13 Charge Sensitive Preamplifier is designed for optimum

performance with Silicon Surface Barrier (SSB) detectors. Operating as a charge to voltage converter, the

unit accepts charge carriers produced in the detector during each absorbed nuclear event. The output

then provides a voltage in direct proportion to the collected charge at the rate of 1.4V per picocoulomb.

This translates to a gain of 62mV per MeV (see table) for room temperature silicon detectors.

For typical use with positively biased SSB detectors, the extremely linear energy output provides a

negative polarity pulse ideal for energy spectroscopy.

The high charge rate capability of the design is evidenced by an energy rate capacity of greater than 10 5

MeV per second when used with silicon detectors. In order to take full advantage of such a high count

rate capabilty, a main amplifier with a correspondingly high count rate ability, such as the FAST ComTec

Model CSA4, should be used.

The basic operation of the preamplifier is indicated in the functional schematic diagram below, see Fig.

1.1. The first stage acts as an operational integrator which produces an output potential proportional to

the accumulated charge on the feedback capacitor Cf. The integrator drives the output buffer with a gain

of +2.

The noise contribution of the preamplifier is only 1.7 KeV, FWHM, (Si) with an increase of less than 34 eV

for each picofarad of additional source capacitance. To reduce noise injected through the HV input, a

decoupling network is utilized for filtering the detector bias voltage.

To reduce the possibility of transmission line reflections when using long lengths of coaxial cable, the

energy output is provided with a series resistor, eliminating the necessity of terminating the line at the

receiving end.

For those applications utilizing lower voltage detectors with vacuum chamber feedthrough connectors or

direct detector cabling inside a chamber, the Model CSPA10...13-1B provides a BNC for the detector and

HV bias input. Necessary power is provided by any FAST ComTec main amplifier through the five foot

compatible cable furnished with the preamp.

6F ComTec Gmb

Introduction

Tables to the CSP10...13

F ComTec Gmb 7

Fig. 1.1: Functional Schematic diagram

Table 1: Sensitivity Versions

Preamp

model

Gain (mV

/picoCoulomb)

Max. detect.

Pulse (e-)

equiv. noise in

silicon keV (FWHM)

CSPA10 1400 107 1.7 keV

CSPA11 150 108 6.0 keV

CSPA12 15 109 65 keV

CSPA13 1.5 1010 230 keV

Table 2: model specifications (noise, risetime)

Preamp

model

noise (ENC)

e- (RMS)*

noise (ENC)

slope e- /pF

rise time

(Cd=0pF)

CSPA10 200 e- 4 e- /pF 7 ns

CSPA11 630 e- 3.7 e- /pF 3 ns

CSPA12 6,800 e- 28 e- /pF 6 ns

CSPA13 24,000 e- 27 e- /pF 20 ns

Table 3: input / Hi h volta e connectors

model Input Connectors input / HV

CSPA1X-2S 2 kV / 10 nF SHV / SHV

CSPA1X-4S 4 kV / 4.7 nF SHV / SHV

CSPA1X-1B 1 kV / 10 nF BNC / BNC

CSPA1X-1BS 1 kV / 10 nF BNC / SHV

Table 4: orderin information

Model No. escription Order No.

CSPA10-2S Charge-sensitive preamp, SHV, 2kV/10nF, 1.4 V/pC CSPA102S

CSPA11-2S Charge-sensitive preamp, SHV, 2 kV/10 nF, 150 mV/pC CSPA112S

CSPA12-2S Charge-sensitive preamp, SHV, 2kV/10nF, 15 mV/pC CSPA122S

CSPA13-2S Charge-sensitive preamp, SHV, 2 kV/10 nF, 1.5 mV/pC CSPA132S

CSPA10-4S Charge-sensitive preamp, SHV, 4kV/4.7nF, 1.4 V/pC CSPA104S

CSPA11-4S Charge-sensitive preamp, SHV, 4 kV/10 nF, 150 mV/pC CSPA114S

CSPA12-4S Charge-sensitive preamp, SHV, 4kV/4.7nF, 15 mV/pC CSPA124S

CSPA13-4S Charge-sensitive preamp, SHV, 4 kV/10 nF, 1.5 mV/pC CSPA134S

CSPA10-1B Charge-sensitive preamp, BNC, 1 kV/10 nF, 1.4 V/pC CSPA101B

CSPA11-1B Charge-sensitive preamp, BNC, 1 kV/10 nF, 150 mV/pC CSPA111B

CSPA12-1B Charge-sensitive preamp, BNC, 1 kV/10 nF, 15 mV/pC CSPA121B

CSPA13-1B Charge-sensitive preamp, BNC, 1 kV/10 nF, 1.5 mV/pC CSPA131B

CSPA10-1BS Charge-sensitive preamp, BNC/SHV, 1kV/10nF,1.4 V/pC CSPA101BS

CSPA11-1BS Charge-sensitive preamp, BNC/SHV,1kV/10nF,150mV/pC CSPA111BS

CSPA12-1BS Charge-sensitive preamp, BNC/SHV, 1 kV/10nF,15mV/pC CSPA121BS

CSPA13-1BS Charge-sensitive preamp, BNC/SHV, 1kV/10nF,1.5mV/pC CSPA131BS

Specifications

2 Specifications

2.1 Inputs

Preamplification channels: 1

up to ± 4000 volts (SHV connector)

± 4000 volts (SHV connector)

Test input 50 ohms terminated fort tail pulser

2.2 Outputs

ecay time constant: 140 µs (150 µs, 50 µs, 50 µs resp.)

Unsaturated output swing: -3 to +3 volts

Output offset: +0.2 to -0.2 volts

Output impedance: 50 ohms

2.3 Performance

Equivalent noise charge (ENC)*: ( see table 1, CSPA10)

ENC RMS: 200 electrons, 0.03 femtoCoul. (CSPA10)

Equivalent noise in silicon: 1.7 keV (FWHM)

Equivalent noise in CdZnTe: 2.4 keV (FWHM)

ENC slope: 4 electrons RMS /pF

Gain: see table 1

Rise time**: 7 ns ( see table 2 page 2, CSPA10 )

Maximum charge detectable per event: (see table 1)

Operating temperature: -40 to +85ºC

• Measured with input unconnected, using Gaussian shaping amplifier with time constant =1 s. With a detector attached to the

input, noise from the detector capacitance, leakage current, and dielectric losses will add to this figure.

** Pulse rise time (defined as the time to attain 90% of maximum value) has a linear relationship with input capacitance. Value cited

in the table assumes zero added input capacitance. o calculate pulse rise time for practical situations, use the equation: tr =0.4 Cd

+ 7 ns, where tr is the pulse rise time in ns, and Cd is the added capacitance (e.g. detector capacitance) in pF.

Keep in mind that other factors within the detection system may further limit this value.

8F ComTec Gmb

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