Dec 8 – 10, 2020 Online only
Online event
Europe/Berlin timezone

CHARM – A fast, high resolution curved 3He-based Multiwire- Proportional Chamber for the powder diffractometers DMC and ERWiN

Dec 9, 2020, 2:30 PM
3h 30m
Online event

Online event


Dr Karl Zeitelhack (MLZ)


The upcoming high-intensity powder diffractometer ERWIN at MLZ and the cold-neutron powder diffractometer DMC at the Paul Scherrer Institut, Switzerland, will be equipped with new fast and high-resolution two-dimensional position-sensitive curved 3He-based Multi-Wire Proportional Chambers (MWPC) covering 130° horizontal and 14° vertical acceptance. The fully modular design is adopted from a development at Brookhaven National Laboratory (BNL) and consists of nine individual MWPC segments mounted seamlessly inside a common pressure vessel filled with a gas mixture of 6.5 bar 3Helium + 1.5 bar CF4. The device with a radius of curvature R = 800 mm is aiming at 75% detection efficiency for thermal neutrons, 1.6 mm x 1.6 mm position resolution (FWHM) and about 200 kHz count rate capability per MWPC segment at 10% event loss. Single channel induced charge readout using a Time-over-Threshold detection method is applied to the 1152 x 1152 individual cathode wires and strips, respectively. For each detected neutron a FPGA-based signal processing electronics developed in-house will provide 2D-position information applying a Centre-of-Gravity algorithm and time stamping with 80 ns time resolution.
First results of measurements performed with a 30°-prototype using a collimated beam of 4.73 Angstrom neutrons at the TREFF instrument at FRM II and the present status of the construction of the full size detectors will be presented.

Primary author


Dr Alan Howard (MLZ) Dr Bruno Guerard (Institute Laue-Langevin ) Mr Dieter Graf (Paul Scherrer-Institut) Mr Ilario Defendi (MLZ) Dr Julian Marchal (Institut Laue Langevin) Dr Malte Hildebrandt (Paul Scherrer Institut ) Mr Max Panradl (MLZ) Peter Wind Rudolf Wildgruber

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