1 / 18

Neutron detector developments at LPC Caen

Neutron detector developments at LPC Caen. b -delayed neutron detectors  current limitations future issues Search for new solid scintillators (Neutromania) Simulations for future neutron arrays Developments of digital electronics. TONNERRE. EXOGAM.

lulu
Télécharger la présentation

Neutron detector developments at LPC Caen

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Neutron detector developments at LPC Caen • b-delayed neutron detectors •  current limitations • future issues • Search for new solid scintillators (Neutromania) • Simulations for future neutron arrays • Developments of digital electronics

  2. TONNERRE EXOGAM b-delayed n detectors : current state of the art TONNERRE array 32 bars, 160 x 20 x 4 cm3 BC400 plastic Up to 45% of 4p Intrinsic en ~ 45% at 1 MeV En from TOF (d=1.2 m) dEn/En ~ 10% Threshold : En ~ 300 keV A. Buta et al., NIM A455 (2000) 412

  3. number of counts 50 100 150 200 250 300 time-of-flight (ns) bn detectors : current limitations 46Cl29 No n-g discrimination : g background dEn/En limited by thickness & dflight • Tails : • slow scintillation component? • light transmission? S. Grévy and the TONNERRE collaboration

  4. bnm + mm + b2n b2n with current detectors Test on 11Li(b)9Be+2n with TONNERRE (F.M. Marqués et al.) • background dominant • n-g discrimination needed

  5. Issues for future b-delayed neutron detectors • n-g discrimination : background reduction, multiple neutrons (eg b2n) •  liquid scintillators or new solid scintillators • improve En resolution • increase distance of flight, thin detectors • cross-talk rejection : multiple neutrons (eg b2n) • modular, high granularity • lower threshold : • thin, small volume detectors, digital electronics, good discrimination From b-n Meeting, LPC, Feb. 2007 & Neutron Detector Workshop, Madrid, July 2006

  6. bxn detectors : plans • Possible test experiment in 2008 : • feasibility of b2n with n-g discrimination • learn about issues • EDEN (NE213, 5 cm thick) and standard electronics • test of digital electronics (LPC or other)

  7. Neutromania at Caen • Sample synthesis at LCMT-ENSICAEN (chemistry lab) : • PMMA- or polystyrene-based polymers • various fluors tested • secondary solvents and/or solutes (naphthalene, POPOP…) Scintillation and discrimination properties tested at LPC with sources • Results : • no major difficulties to obtain scintillation • some samples show high light output (~BC400) • discrimination is challenging • no sample shows discrimination T. Dalet et al., in preparation • Understand discrimination mechanisms : • test of current solid & liquid scintillators

  8. Discriminating plastic « plastic 77 », Brooks et al, IRE Trans. Nucl. Sci., NS-7, 35 (1960) • No exotic compounds (similarities with NE213) • Light output ~ BC400 • Clean synthesis process (CEA Saclay) Test at LPC with digital ADC : 2 GHz, 12 bits, 2500 samples (1.25 ms), low rate Qtotal Qslow neutrons g neutrons g

  9. Geant4 simulations • Design future neutron detectors for • fast neutrons from breakup reactions (Eurisol) • b-delayed neutron spectroscopy (Spiral2, Eurisol) •  2 year postdoc (Eurisol DS, task 10), Brian Roeder • Why Geant4 ? • handles complex geometries • tracking built-in • lots of available physics models for particle interactions But need to validate

  10. Geant4 issues } built-in elastic & inelastic models } inelastic cross-sections from Menate No satisfying models B. Roeder

  11. Geant4 simulations with home-made model • Develop our own models • Start with low energy elastic scattering on H & C • Data-based model Good at low energy Add inelastic scattering… B. Roeder

  12. Geant4 simulations with home-made model Home made Looks good Add inelastic scattering… B. Roeder

  13. Digital electronics developments • Current developments : • Fast DAQ, « FASTER » • Digital Spectroscopy Amplifier • Planned developments : • Digital CFD • Digital trigger • Neutron-detector dedicated electronics • Issues for n-detector electronics : • What ADC sampling rate do we need for timing ~500 ps? • What resolution for Qslow/Qfast? • Improve n-g discrimination? TOF Qslow Qfast Detector ADC FPGA CFD, gates... PhD starting Nov. 2007 D. Etasse et al

  14. Conclusions & Outlook • New materials : • solids can discriminate n & g • why? how? • Feasibility of b2n : • test experiment with thin detectors & discrimination (~2008) •  issues, improvements • Design of future n-detectors : • simulations being tested & improved • special emphasis on cross-talk performances (multiple neutrons) •  first designs in 2008/2009 • Digital electronics : • developments in the next 3 years (PhD) • test experiment ~ 2008 • improve n-g discrimination?

  15. The DEMON array Neutrons from break up reactions @ tens of AMeV 96 modules, 16 x 20 cm2 (4 liters) NE213 liquid scintillator n-g discrimination En from TOF (d~3 m) Modular : position, solid angle, cross-talk rejection En threshold ~ 2 MeV Intrinsic en > 30 % for 3 < En < 60 MeV Angular acceptance ~ 30%

  16. DEMON & digital electronics Test at LPC with digital ADC : 2 GHz, 12 bits, 2500 samples (1.25 ms), low rate Qslow vs Qfast 137Cs source Qslow vs Qfast AmBe source

  17. DEMON efficiency with Menate DEMON intrinsic efficiency Efficiency MENATE simulation • Reactions : • H(n,n) • 12C(n,n) • 12C(n,n’g) • 12C(n,2n) • 12C(n,a) • 12C(n,n’3a) • 12C(n,p) • 12C(n,np) 500 keVee threshold H(n,n) All processes C(n,n’3a) C(n,np) C(n,p) C(n,a) Neutron energy (MeV) Simple Reasonably accurate Only cylindrical detectors with NE213 scintillator P. Désesquelles et al, NIM A 307, 366 (1991)

  18. n-g discrimination with digital electronics • With digitized n & g signals (eg from DEMON) : • discrimination with Qslow/Qfast comparison : • optimal gates • event by event baseline correction • no signal splitting • discrimination threshold? • En threshold? • better separation? • develop & test new discrimination algorithms

More Related