1. Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP – CTU Prague 1 Current status and future development of neutron detectors based on Timepix technology Frantisek Krejci, Jan Jakubek, Zdenek Kohout, Stanislav Pospisil, Tomas Slavicek, Jan Zemlicka Institute of Experimental and Applied Physics, Czech Technical University in Prague Many thanks to: Institut Laue Langevin, Grenoble, France Paul Scherrer Institute, Villigen, Switzerland Nuclear Physics Institute AS CR, Rez near Prague, Czech Republic Research Centre Rez, 25068 Husinec-Rez 130, Czech Republic Medipix collaboration BrightnEES Kick-off meeting, Lund 25/9/2015Frantisek Krejci

2. Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP – CTU Prague 2 Particle counting pixel detectors (Hybrid pixel technology) BrightnEES Kick-off meeting, Lund 25/9/2015Frantisek Krejci (Si) Amplifier Compa- rator(s) Counter: Particle count 000001 Pixel electronics + Bias Voltage Threshold Level(s) Pilatus - PSI 60 x 97 pixels Pitch of 172 um Counter: 20 bits Single threshold Module 16 chips Large area - tilling Medipix2 – CERN 256 x 256 pixels Pitch of 55 um Two thresholds Module 6 chips Large area: RELAXd Timepix - CERN Time stamp Energy measurement in each pixel

3. Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP – CTU Prague 3 BrightnEES Kick-off meeting, Lund 25/9/2015Frantisek Krejci Principle: Semiconductor pixel detector can barely detect slow neutrons directly.  Conversion of thermal neutrons to detectable radiation in a suitable material is needed. Placement of a converter: on the sensor surface (coated detector), inside of the sensor volume (stuffed detector), converter is a component of the sensing material. Converter materials:Cross section 6 Li: 6 Li + n   (2.05 MeV) + 3 H (2.72 MeV)940 barns 10 B: 10 B + n   (1.47 MeV) + 7 Li (0.84 MeV) +  (0.48MeV)(93.7%) 10 B + n   (1.78 MeV) + 7 Li (1.01 MeV) (6.3%)3 840 barns 113 Cd: 113 Cd + n  114 Cd +  (0.56MeV) + conversion electrons26 000 barns 155 Gd: 155 Gd + n  156 Gd +  (0.09, 0.20, 0.30 MeV) + conversion electrons 157 Gd: 157 Gd + n  158 Gd +  (0.08, 0.18, 0.28 MeV) + conversion electrons~60 000 barns Adaptation of the pixel device for slow neutron detection Neutron beam back side contact grid e n

4. Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP – CTU Prague 4 BrightnEES Kick-off meeting, Lund 25/9/2015Frantisek Krejci Neutron micro-radiography Wrist watch Metallic cover was fixed on watch in time of measurement ! Exposition time = 500 seconds Planar 6 LiF converter on the Mexipix2 chip

5. Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP – CTU Prague 5 Recent challenges: Large field of view sd BrightnEES Kick-off meeting, Lund 25/9/2015Frantisek Krejci Shown without neutron converter  Neutron radiography of Ethernet extender  Cold neutron beam at PSI used (NEUTRA) Single chip area

6. Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP – CTU Prague 6 Recent challenges: Micrometer spatial resolution BrightnEES Kick-off meeting, Lund 25/9/2015Frantisek Krejci  Cold neutron beam at PSI used (NEUTRA)  Gadolinium Siemens Star patter  Spatial resolution 2.5 µm thanks to tracks centroiding  256 × 256 pixel chip provides 26 Mpx image

7. Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP – CTU Prague 7 Recent challenges: 3D sensor structures for higher efficiency BrightnEES Kick-off meeting, Lund 25/9/2015Frantisek Krejci Neutron beam back side contact grid  Single layer planar arrangement of converter and sensor can have max about 4% neutron detection efficiency ( 6 Li)  Detection efficiency can be increased with multilayer arrangement and sensor surface 3D area extension

8. Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP – CTU Prague 8 BrightnEES Kick-off meeting, Lund 25/9/2015Frantisek Krejci Conclusions  Hybrid semiconductor pixel detectors can be very successfully adapted for neutron detection  The spatial resolution can be very high (microns)  The event-by-event (tracking) technique analyzing collected charge shape is powerful technique  Very high background suppression – electrons (e.g. from gamma scattering) have different tracks  Technology development leading to further spatial resolution and sensitivity improvement is in progress (novel sensor materials such as B 4 C, 3-D sensors, …)

9. Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP – CTU Prague 9 Thank you for your attention BrightnEES Kick-off meeting, Lund 25/9/2015Frantisek Krejci