Introduction to our institute: WWW page: http://www.psi.ch/

Laboratory for Neutron Scattering (LNS): http://www.psi.ch/lns
Spallation Neutron Source (SINQ): http://www.psi.ch/sinq

1. Detectors in use and being developed:

i) Single Detectors, as used in the DrüchaL, TASP and TOPSI instruments:
In this spectrometers we use He-3 detectors with the following specifications
(comercially available from EURISYS MESURES, Z.A. de l’ Observatoire - 4 Avenue des Frênes, F-78067 St Quentin Yvelines Cedex):
1. active length : 17cm
2. He-3-pressure : 5 bars
3. cross-section : diameter 5cm
4. high voltage : 1500 V
5. gas amplif. : ca. 22 @ 1500V, ( i.e. 15.5 .. 66 fC/neutron )
6. background : < 20 counts/h
7. efficiency : > 98% for lamda > 1 A
8. anode wire : Tungsten, 50 mu-meter thick, spring loaded
9. detector body : stainless steel, wall thickness: 0.5 mm
10. manufacturer : Eurisys Mesures/Dextray
11. type : 73NH17/5X
12. det. capacitance : 23 pF

ii) Single Detectors, as used in the FOCUS instrument:
At the new neutron spallation source SINQ a Time-of-Flight spectrometer is under construction, being designed for cold neutrons. The project is named FOCUS and it is a cooperation between the university of Saarbruecken and the PSI, Villigen.
It is foreseen to equip the spectrometer at the beginning of its operation with 200 He-3 detectors with the following specifications:
1. active length : 40cm
2. He-3-pressure : 6 bars
3. cross-section : rectangular (3cm width x 1cm depth)
4. high voltage : 1050 V
5. gas amplif. : ca. 15 @ 1050V, ( i.e. 10.5 ..45 fC/neutron )
6. background : < 20 counts/h
7. efficiency : > 87% for lamda > 4 A; > 95% for lamda > 6 A
8. anode wire : Tungsten, 50 mu-meter thick, spring loaded
9. detector body : stainless stell, wall thickness: 0.5 mm
10. manufacturer : Eurisys Mesures/Dextray
11. type : 90NH40REC
12. det. capacitance : 30 pF

iii) Neutron beam monitors:
comercially available from LND (Designers & Manufacturers of Nuclear Radiation
Detectors, 3230 Lawson Boulevard, Oceanside, NY 11572).
Specifications:
1. efficiencies : 1.0E-3, .. 1.0E-7
2. high voltage range : 400 .. 800 V (typ. 500V)
3. gas filling : Ar-CH4
4. gas pessure : 760 torr
5. charge/pulse : source Po-Be: 550 fC,
(measured @ ill: mean of distribution: ca.130 fC)

iv) 1D detectors for the instruments DMC and HRPT (MWPC’s)
DMC: L.M.T. multidetector type LC 400 CP N° 6, produced/delivered: 1984.
1. aperture angle : 80°
2. radius of detector : 1500 mm
3. number of det. wires : 400, (i.e. angular resolution = 0.2°)
4. Al window thickness : 4mm, (i.e. 4 % absorption for 1.8 A neutrons)
5. gas filling : BF3 (isotope B-10 enrichment 90 % minimum)
6. gas pressure : 750 torr (depth of detection = 45 mm)
7. detection yield : > 40% for lamda > 1.8 A
8. high voltage : 5000 V
9. gas amplif. : ca. 10 @ 5000V, ( i.e. ca. 100 fC/neutron )
10. max. cnt.-rate/cell : 3’000 cnts/sec
11. max. det. cnt.-rate : 50’000 cnts/sec

HRPT: CERCA multidetector type LCP 1600 - 2,6 x 150,
(delivery to PSI planed: Dec. 97)
(at CERCA a working prototype LCP 128 - 0,1° exists)
1. aperture angle : 160°
2. radius of detector : 1500 mm
3. number of det. wires : 1600, (i.e. angular resolution = 0.1°)
4. Al window thickness : 10mm, (i.e. 10 % absorption for 1.8 A neutrons)
5. gas filling : He-3; CF4
6. partial gas pressures : 3 bar; 1 bar (depth of detection = 40 mm)
7. detection yield : >62 % for lamda > 1.2 A; >82 % for lamda > 2.4 A
8. high voltages (proto) : 1st cath.-4’175V, anodes +1’200V, 2nd cath.-7’900V
9. gas amplification : ca. ?? @ operating cond., ( i.e. ca. ?? fC/neutron )
10. max. cnt.-rate/cell : 30’000 cnts/sec
11. max. det. cnt.-rate : 500’000 cnts/sec

v) 2D detector for the SANS instrument (MWPC)
CERCA multidetector type XYP 128 x 128 -7,5; (delivery to PSI Dec. 96)
(we have still problems with the digital part of the NIDOS electronic)
1. active area : 96 x 96 cm2
2. 2D resolution : 7.5 x 7.5 mm2 (i.e. 16’000 detection cells)
3. number of det. wires : 128 x 128
4. Al window thickness : 7 mm + 2 mm, (i.e. 9 % absorpt. for 1.8 A neutrons)
5. gas filling : He-3; CF4
6. partial gas pressures : 2.3 bar; 0.7 bar (depth of detection = 25 mm)
7. detection yield : >66 % for lamda > 2.4 A
8. high voltages : anode +2’700V, cathodes +200V
9. gas amplification : ca. ?? @ 2’500 V, ( i.e. ca. ?? fC/neutron )
10. max. cnt.-rate/cell : 30’000 cnts/sec
11. max. det. cnt.-rate : 200’000 cnts/sec

vi) 2D m -strip detectors (MSGCs) for the TriCS instrument
(and for other instruments in the near future, too.)
A new type of neutron m -strip detector (PSI 203) is currently being developped in
close collaboration with A. Oed, ILL, Grenoble. The layout parameters of this 8 inch
by 8 inch 2D He-3 detector are:
1. active area : 172 x 190 mm2
2. glass type : Schott S 8900, 0.5 mm
3. substrate : chromium 200 nm, sputtered twice
4. anode width (front) : 12 m m
5. numb. of anode strips: 190
6. anode/anode separ. : 1’000 m m
7. resistive line width : 40 m m
8. line resistance (front): 14 k Ohm
9. resolution (front) : 1.5 .. 2 mm
10. cathode width (front) : 500 m m
11. cath. line resistance: 40 Ohm
12. cathode width (back) : 960 m m
13. numb. of cath. strips 172
14. cathode/cathode gap : 40 m m
15. line resistance (back): 13 k Ohm
16. resolution (back) : 2 .. 2.5 mm
17. gas filling : He-3; CF4
18. partial gas pressures : 4.5 bar; 1.5 bar (depth of detection = ?? mm)
19. detection yield : >?? % for lamda > ?? A
20. high voltage : 1’500 V max.
21. gas amplification : ca. ?? @ 1’500 V, ( i.e. ca. ?? fC/neutron )
22. readout resolution : 256 x 256 pixels
23. max. det. cnt.-rate : 50’000 cnts/sec

2. Detectors planned to be bought or developed in the next years:

i) for the FOCUS instrument:
One possible future option for a new development is a 2D-small angle detector with time-of-flight analysis, i.e. a detector for neutron Brillouin scattering.
FOCUS responsibles at PSI: Stefan Janssen,
mechanical design: Lothar Holitzner
detector design: Johny Egger
electronics: Nick Schlumpf

ii) for the TriCS instrument:
Further development of the MSGC (BiDim ILL type PSI 203) detector system.
TriCS responsibles at PSI: Jürg Schefer,
mechanical design: Max Koch, Rudolf Thut
electronics: Nick Schlumpf

iii) for the Neutron-Reflectometer (AMOR):
We are looking for a fast detector- and readout-system to be used for time of flight measurements with this reflectometer; the most important design parameters are:
1. high lateral resolution: TBD mm,
2. active area : 10 x10 cm2
3. detection yield : >60 % for lamda > 1.0 A; >90 % for lamda > 16 A
4. backgnd cnt-rate : TBD cnts/h (max.)
5. sensitivity to gammas: minimized
6. readout resolution : TBD x TBD pixels
7. max. det. cnt.-rate : TBD cnts/sec
Reflectometer responsible at PSI: Daniel Clemens

iv) for the Multiple Pulse Overlap Diffractometer (POLDI):
At PSI we just started the design phase for a 1D-detector with time-of-flight analysis;
the most important design parameters are:
1. aperture of detector : 30Á ,
2. spatial resolution : 2 mm,
3. detection yield : as high as possible (therm. neutrons),
4. backgnd cnt-rate : minimized
5. sensitivity to gammas: minimized
6. time resolution : <= 2 m sec,
7. number of cells : ca. 500,
8. detection depth : 20..50 mm.
POLDI responsible at PSI: Uwe Stuhr,
mechanical design: Jaroslav Kohout,
detector design: Johny Egger,
electronics: Nick Schlumpf

v) 2D detection system for Neutron-Radiographie (NEUTRA):
In the future we would like to increase the resolution of the CCD-camera readout system to (1024 x 1024) or even better to (2048 x 2048) pixels.
Neutron-Radiographie responsible at PSI: Eberhard Lehmann

3. Special abilities of our labs:

i) Developement, design and assembly of MSGCs,
please contact: Jürg Schefer

ii) Developement, design and assembly of MWPCs
please contact: Johny Egger

iii) Developement and design of front end electronics and data aquisition
please contact: Nick Schlumpf

iv) Knowledge and experience in the field of neutron radiographie
please contact: Eberhard Lehmann

4. Simulation SW packages used in our labs:

i) Drift chamber simulation program: GARFIELD version: 5.02
(" Rob Veenhof, 1994, all rights reserved)
available from the CERN Program Library: entry: POOL-W5050
language: FORTRAN
for additional informations please contact: Johny Egger

ii) Particle transport code (Monte Carlo): MCNP version: 4a
freely available from the Los Alamos labs
for additional informations please contact: Eberhard Lehmann

iii) Particle transport code (Monte Carlo): GEANT version: ??
available from the CERN Program Library: entry: ??
language: FORTRAN
for additional informations please contact: Wojtek Hajdas

iv) An electrical cirquit simulation program: PSpice A/D version: 7.1
(" MicroSim corporation, 1996, all rights reserved)
commercially available
for additional informations please contact: Nick Schlumpf

5. Special equipements available in our labs:
------ clima chamber , & ??

6. Frontend electronics and data aquisition systems used in our labs:.

i) A commercially available PC-card based multiparameter system together with the MPAWIN SW system are used in our Multi-Detector test setups.
(" , 1993-95 FAST Com Tec Communication Technology GmbH, Munich, Germany.
All rights reserved)
for additional informations please contact: Jürg Schefer

ii) Together with an industrial partner (Eurisys Mesures/Dextray) we developed /
modified a charge preamplifier (ACHP96) for our Mono-Detectors and Neutron-Beam-Monitors as described in items 2.i) .. 2. iii). This amplifier has a built in high voltage filter (max. 3 kV), a 50 Ohm terminated test pulse input and the following features:
high sensitivity (Mono-Detectors) : >= 40 mV/fC for Cdet. <= 200 pF
(Beam-Monitors) : >= 10 mV/fC for Cmon. <= 200 pF
low noise (ENC @ Cdet. = 0 pF) : < 600 electrons rms (i.e. < 0.1 fC rms)
noise slope : < 6 electrons rms / pF
analog output impedance : 50 Ohm
adjustable threshold (logic output) : 50 mV ... 1.2 V
logic output (standard) : 50 Ohm, (level: TTL compatible)
(optional) : ligth wave guide driver
time jitter (analog/digital outputs) : <= 100 nsec (for gas gain >= 15 in
He-3 detectors)
count rate (< 5 % dead time) : 30’000 cps (TBC)

for additional informations please contact: Nick Schlumpf

iii) We are currently developping a multi purpose Multi-Detector readout System consisting of:
1) a programable interface unit using FPGA's. This IF will easily be adaptable to
all one- and two-dimensional detection systems at SINQ and will allow for
i) event time stamping,
ii) dead time measurement and
iii) in the case of multiple input sources for coincidence timing among this
sources (up to 9 input connectors with one 16 bit data word each, are
forseen).
2) An optical point to point data transmission system (4 kByte FIFO to derandomize the incomming events, TAXI chip set) with a capacity of 100 Mbit/sec, and
3) a fully programmable data reduction system (Histogram Memory) based on a
Power PC VME module running the RT-OS VxWorks.

for additional informations please contact: Nick Schlumpf

iv) We have developed a Neutron-Counter/Ratemeter („normalization unit") for the
instruments at our spallation neutron source SINQ. This unit provides a low rate gate (HW output to gate our Multi-Detector readout System is available) in order to
eliminate „noise build up" during accelerator drop outs in the data aquisition system.
This unit accepts up to 8 sources (TTL compatible inputs, or optionally, ligth wave
guide receiver inputs are available), has remote programable preset time and preset
count modes and delivers data to a host computer through a RS 232 serial line.

for additional informations please contact: Nick Schlumpf

v) Our step motor controller is widely used in all spectrometers to fullfill the precise
positioning requierements. This unit allows us to control up to 12 motors (2 phase,
or 5 phase types) in the open or closed loop configurations from one single RS 232
serial line.
....
for additional informations please contact: Nick Schlumpf

vi) An other useful unit is our magnet controller front-end. In order to remotely adjust up
to 8 magnetic fields, we are able to set the corresponding current supplies to the
appropriate values via one RS 232 line, too.

for additional informations please contact: Nick Schlumpf

vii) Further, we are using on each instrument the Siemens PLC System S7 / 300 to
perform various steering and measuring tasks. This module is remotely controllable
via a RS 232 line, too.

for additional informations please contact: Nick Schlumpf

Nick Schlumpf, September 9, 1998