ERINDA PAC 1/4 Testing the UAB Extended Range Bonner Sphere Spectrometer for high energy neutrons UU-TSL, Uppsala, Sweden UAB Barcelona

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1 ERINDA PAC 1/4 Testing the UAB Extended Range Bonner Sphere Spectrometer for high energy neutrons UU-TSL, Uppsala, Sweden UAB Barcelona ERINDA PAC 1/9 Measurement of the total neutron spectrum close to the target of the PIAF reference monoenergetic neutron fields PTB, Braunschweig, Germany UAB Barcelona 1

2 ERINDA PAC 1/3 Characterisation of a novel neutron spectrometer based on a single moderating sphere UU-TSL, Uppsala, Sweden LNF-INFN Frascati ERINDA PAC 1/8 Characterisation of a novel neutron spectrometer based on a single moderating sphere using mono-energetic neutron beams below 20 MeV PTB, Braunschweig, Germany LNF-INFN Frascati 2

3 Progress Report Overview Overall aim DETECTORS BSS Track detectors IRRADIATIONS PTB-PIAF UU-TSL RESULTS (preliminary and in progress) PTB-PIAF UU-TSL 3

4 Overall aim Development of new detector (INFN-NESCOFI) Pb Need to compare to well known detectors UAB measures with extended Bonner Sphere Spectrometer (needs also characterisation for E>20 MeV) R =

5 DETECTORS 5

6 Bonner sphere spectrometry Principles A thermal neutron sensitive detector is placed at the centre of each polyethylene sphere of a set having different diameters As the sphere diameter increases the maximum of its sensitivity shifts to high energies From the reading M i of each sphere i and once known its response function R i (E), the neutron spectrum is obtained by unfolding the corresponding equation matrix for the n spheres used: M1 R1 ( E) E ( E) de M n R ( E) n E ( E) de 6

7 Bonner sphere spectrometry Principles Extended BSS is able to cover 12 energy decades, from thermal to GeV Limited energy resolution Combining BSS with information obtained by other means (experimental or simulation) improves resolution 7

8 Bonner sphere spectrometry The UAB spectrometers 8 polyethylene spheres (diameters: 2.5", 3", 4.2", 5", 6", 8", 10" and 12" inches) of 0.92 g/cm 3 density and a spherical Cd cover (1 mm thick) used with the three smallest ones Passive BSS: Gold activation foils 197 Au(n,p) 198 Au 99.99% purity 15 mm diameter 110 m thick 0.38 g mass counts/channel Active BSS: 3 He proportional counter 3 He(n,p) 3 H Channel Response function evaluated from simulation with MCNPX and validated experimentally in the past with in monoenergetic fields and ISO sources. Up to 20 MeV. 8

9 Bonner sphere spectrometry TheextendedspectrometersXBSS 3 new spheres were built: 7 polyethylene 7 + Cu: 3 polyethylene + 1 Cu shell (inset) + polyetylene up to Pb: 3 polyethylene + 1 Pb shell (inset) + polyetylene up to 7 Metal insets enhance the (n,xn) reaction Extend the range of applicability up to the GeV range Response function calculated, need to validate 9

10 Bonner sphere spectrometry Unfolding FRUIT unfolding tool Collaboration UAB/LNF-INFN Evolution of previous code MITOM Parametric / Mathematical Based on Physics Estimation of all uncertainties User-friendly interface User may operate while unfolding 10

11 Track detectors The UAB stack Polyethylene: proton production from fast neutrons by elastic scattering Makrofol polycarbonate: less H content, flattens response function Polyethylene (3mm) Makrofol (300 m) Nylon (100 m) CR - 39 (500 m) Methacrylate (5mm) Nylon: 626 kev protons originated from thermal neutrons Phantom (15cm) CR-39 (PADC): records protons within its registration window (100 kev 5 MeV) A Pb cover extends its response to high energy neutrons 11

12 Track detectors Electrochemical etching and readout 12

13 IRRADIATIONS 13

14 PTB-PIAF (Erinda PAC 1/8) Monochromatic energies: 144 kev, 565 kev, 1.2 MeV, 5 MeV, 14.8 MeV Active BSS + Track detectors 14

15 UU-TSL (Erinda PAC 1/3) Active and passive XBSS Track detectors 15

16 UU-TSL (Erinda PAC 1/3) Active and passive XBSS Track detectors 16

17 RESULTS (preliminary) 17

18 PTB PIAF Active BSS 18

19 PTB PIAF Fluence rates 144 kev 565 kev 1,2 MeV 5 MeV 14,8 MeV (cm -2 s -1 ) 196,01 772,97 947, , ,14 (cm -2 s -1 ) 1, ,84 37,40 40,18 19

20 PTB PIAF Track detector counts 20

21 UU-TSL Active BSS 21

22 UU-TSL Reference Provided by Elke Passoth report 6 Dec

23 UU-TSL Fluence rates 50 MeV Unfolded TOTAL: (14.77 ± 0.25) 10 3 cm-2 s-1 Average reference PEAK: (7.33 ± 0.25) 10 3 cm-2 s-1 50 MeV 100 MeV 150 MeV 180 MeV ANITA (cm -2 s -1 ) 14767, , , , ,77 (cm -2 s -1 ) 252,80 272,92 214,43 316,65 60,18 23

24 UU-TSL Fluence rates Pile up influence? 24

25 Conclusion Much work still to be done!!! 25

26 The End Thank you! 26