IEAP – CTU Prague Measurement of neutron flux during irradiation in NPI Řež T. Slavíček, V. Linhart, S. Pospíšil Institute of Experimental and Applied Physics, Czech Technical University in Prague, Czech Republic

Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP – CTU Prague 2 Outline Motivation: Independent measurement of neutron flux for radiation hardness study of HEC cold electronics Analysis of homogeneity of the neutron beam Origin of our radiation monitors – RADMON group P-i-n diode BPW34F Measurement and results Conclusion Tomáš Slavíček

Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP – CTU Prague 3 Institute of Experimental and Applied Physics The Institute bases its activity from the following long-term programs: Fundamental experiments in Physics of the Microworld Cooperation with CERN Research Center "Material analysis and characterization by radiation" Research Center "Astroparticle and Astrophysics experiments" Tomáš Slavíček

Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP – CTU Prague 4 Origin of our radiation monitors LHC Experiment Radiation Monitoring Working Group (RADMON), special thanks to Maurice Glaser for his help More information can be found: Development and Characterization of Radiation Monitoring Sensors for the High Energy Physics Experiments of the CERN LHC Accelerator, Federico RAVOTTI, doctoral thesis From various radiation monitors tested by RADMON we chosen p-i-n diode BPW34F Φ(E > 140keV) = 1E11 – 4,7E14 n eq /cm 2 Tomáš Slavíček

Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP – CTU Prague 5 Produced by OSRAM, SIEMENS, TELEFUNKEN, etc. Applications Photo-interrupters IR remote controls BPW34F B = silicon, P = radiation sensitive diode, W34 = serial number, F = DIL plastic package ~3x3 mm 2 silicon die (the active part of the component) Thickness W = 210 µm, ρ = 2.5 kΩ*cm Fluence is calculated from the difference of the forward voltage (ΔV F ) before and after irradiation P-i-n diode BPW34F Tomáš Slavíček

Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP – CTU Prague 6 Dependence of V F on Φ Fluence from 1E11 to 6E12 n eq /cm 2 : Φ [n eq /cm 2 ] = E+12* ΔV F ^ E+13* ΔV F ^ E+13* ΔV F E+10 ΔV 20 o C Fluence 6E12 to 4.7E14 n eq /cm 2 : Φ [n eq /cm 2 ] = 9.10E+09* ΔV F ΔV 20 o C Annealing: 8% after 200 room temp for diode of 1E14 n eq /cm 2 Tc, Negative Temp coefficient (NTC): V 20 o C = V F - [( 8.315E-13 * Φ + 2.3)/1000 * (T-20)] BPW Global Error  ± 20% Tomáš Slavíček

Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP – CTU Prague 7 Measurement I – preparation of IEAP CTU in Prague, determination of initial values of neutron flux monitors – installation of flux cyklotron 12:00 start of irradiation 12:00 temperature inside irradiation area 25 °C/ 48% humidity, stable all along the irradiation – 12:00 end of irradiation (duration of irradiation hours, total charge Q = 2,18 C) 12:31 start of measurement of values after irradiation, room temperature 24,1 °C 13:36 end of measurement 14:30 monitors stored inside freezer to store irradiation damage for later measurement – 10:00 monitors took out from freezer for re- measurement, room temperature 26 °C 11:05 start of re-measurement of new values after irradiation 12:35 end of re-measurement, monitors freezer CERN, 22nd July 2008Tomáš Slavíček Neutron flux monitors (position 6. and 11.; 89,5 mm and 174,5 mm from target) Irradiated parts Neutron source Neutron flux

Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP – CTU Prague 8 Results – position 6 Tomáš Slavíček

Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP – CTU Prague 9 Results – position 11 Tomáš Slavíček

Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP – CTU Prague 10 Results – comparison CERN, 22nd July 2008Tomáš Slavíček

Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP – CTU Prague 11 Conclusion Values of neutron flux in two positions were measured Neutron beam is close to be homogeous within error assigned to monitors P-i-n diode BPW34F is practical tool for neutron measurement Influence of support materials on measurements has to be investigated to estimate the built-up effect Tomáš Slavíček

Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP – CTU Prague 12 Thank you for you attention!!! CERN, 22nd July 2008Tomáš Slavíček

Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP – CTU Prague 13 Measurement II. Measurement of V F HV source meter Keithley 2410  setting: Source I, measure V, Cmpl = 0,2 kV Config sweeps P0000 = 10uA P0001 = 1mA … V F P0002 = 10uA P0003 = 0,1uA Config speed: NPLC = 0,8 vary with irradiation Tomáš Slavíček

Institute of Experimental and Applied Physics Czech Technical University in Prague IEAP – CTU Prague 14 Heavy water target A design sketch of the heavy-water flowing target chamber: 1 - water cooled diaphragm with interchangeable carbon slit, 2 - insulator, 3 - repeller of electrons, 4 - inlet of heavy water flow, 5 – Mo/Ta foil, 6 - target chamber CERN, 22nd July 2008Tomáš Slavíček