Summary of Contents for FAST ComTec 2128N
- Page 1 2128N Constant Fraction Discriminator User Manual © Copyright FAST ComTec GmbH Grünwalder Weg 28a, D-82041 Oberhaching Germany Version 1.2, May 11, 2021...
- Page 2 Version 1.0, May 11, 2021 ComTec GmbH...
- Page 3 The wide dynamic range of the pent CFT permits Multicolor Count Rate Indicator DC coupling DESCRIPTION The Model 2128N replaces the Model 2128. It is a fully dc-coupled constant fraction discriminator with a dynamic range of up to 1000:1. Selectable fraction and three operating modes provide optimum time resolution for many detector types and applications.
- Page 4 - threshold setting supplied externally via rear panel connector - signal shaping using small fractions and RC shaping by modifying f and capacitors. 2128N 11052021 Grünwalder Weg 28A 82041 Oberhaching Germany phone: +49 (0) 89 665180 0 fax: +49 (0) 89 665180 40...
- Page 5 D-82041 Oberhaching, Germany. All rights reserved. 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, D-82041 Oberhaching, Germany. Tel: +49 89 665180-0, FAX: +49 89 66518040 mail: info@fastcomtec.com...
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Page 6: Table Of Contents
Table of Contents 1 Introduction..............................6 1.1 General description..........................6 1.2 Setup information........................... 6 1.2.1 Selection of modes........................6 1.2.2 Fraction............................6 2 Specifications..............................7 2.1 Inputs..............................7 2.2 Outputs..............................7 2.3 Controls..............................7 2.4 Indicators............................... 7 2.5 Performance............................8 2.6 Delay cable............................ - Page 7 Table of Figures Fig. 3.1: The Front Panel..........................9 Fig. 7.1: The Circuit diagram........................... 14 Fig. 7.2: The Board............................15 ComTec GmbH...
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Page 8: Introduction
The two independent negative NIM current outputs are derived as fixed width pulses (see also section 3 and 4). The wide dynamic range of the model 2128N permits its use in many timing applications without the need of fast pulse amplifiers. -
Page 9: Specifications
≥ 700ps typically, = 50Ω; dc-coupled front panel BNC connector; minimum input width ≥ 1 ns, in the LET mode the CFD 2128N accepts shorter input pulses Delay two BNC connectors for an external delay cable in order to form the internal constant fraction signal. -
Page 10: Performance
Specifications 2.5 Performance Dynamic range 1000:1 (regarding the linearity of the input pulses) Walk (CFT mode) in CFT mode for a 1 ns rise time input pulse over a 100:1 dynamic range (reference – 2.5 V) ≈ 60 ps: typically ± 30 ps Count rate up to 100 MHz, limited by dead time (width setting) Pulse pair... -
Page 11: Controls, Connectors And Indicators
Controls, connectors and indicators 3.1 Front panel Threshold sets threshold from -5mV to -1,0V for signal acceptance Input accepts -5mV to -3.0V linear pulses min. input pulse width = 700ps Delay for external delay cable used in CFT and CFRR modes Walk adjust varies zero crossing discriminator Walk inspect allow observation... -
Page 12: Operation
CF timing mark. Some loss in the count rate is obvious. In the LET mode the model 2128N can be used as a simple leading edge trigger up to very high count rates. The leading edge mode should only be used with signals having a very short rise time and a very limited range of amplitudes as change in amplitude will cause walk (see also section 5.1). -
Page 13: Delay Cable
4.2.5 Outputs The output pulses from the model 2128N are intended to drive 50Ω loads through any reasonable length of suitable 50Ω coaxial cable (such as RG-58). As the setting of the width of the positive output signal is consistent with the internal dead time, the user should set this control due to the requirements of the pulse rate for the given experiment. -
Page 14: Circuit Description
Circuit description 5.1 General The model 2128N provides the advantage that various modes of operation (CFT, CFRR, LET) can be chosen by selecting the front panel switch. The fraction (factory set to f = 0.4) can be changed with the resistors R and R on the printed board. -
Page 15: Special Features And Options
Special features and options In this section some special features of the model 2128N which are available on request are listed. 6.1 Power supply Normally ± 6 V from a standard NIM BIN, or on customer request, ± 12 V from a NIM BIN. Or on customer request, 220 V (ac)/110 V (ac) independent from a NIM BIN. -
Page 16: Diagrams
Diagrams Diagrams 7.1 Circuit diagram Fig. 7.1: The Circuit diagram ComTec GmbH... -
Page 17: Board
Board Fig. 7.2: The Board ComTec GmbH...