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Optimizing Light Output Simulations for NEDA Neutron Detectors

Explore the importance of the light-output response in scintillators and its impact on efficiency and cross-talk effects for NEDA neutron detectors. Get insights into light-output estimation and parametrization, and understand its significance in realistic signal intensity evaluation. Discover calculations for light output generated by neutrons and the factors influencing the scintillator's light response. Enhance your knowledge on key parameters such as efficiency and cross-talk for NEDA detectors.

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Optimizing Light Output Simulations for NEDA Neutron Detectors

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  1. LIGHT-OUTPUT SIMULATIONS FOR NEDA Andrea Gottardo Università di Padova “Universa Universis Patavina Libertas” NEDA meeting

  2. Plan of presentation • Introduction : The importance of light-output response in scintillators • Calculations for light-output produced by neutrons • Light-output spectra • First estimations of efficiency and cross-talk for NEDA • Conclusions NEDA meeting

  3. Light-output response: why? The light-output response of a scintillator has to be addressed carefully when estimating the efficiency or the cross-talk effect In fact, the actual signal intensity from a PMT depends on the light-output. Scintillator PMT light charge Neutron electronics Neutrons with the same energy do not always produce the same light output, i.e. the same signal intensity NEDA meeting

  4. Scintillator light response • The energy of the particle(s) scattered by collisions with the incoming neutrons • The kind of the particle(s) scattered by collisions with the incoming neutrons • Other characteristics of the scintillator such as the optical coupling to the PMT, the light transport and reflection in the scintillator itself… The light-response depends on: NEDA meeting

  5. Light-output importance for NEDA Realistic estimation of the intensity of output signals Simulation for neutron detector J. Ljungvall et al., NIM A 528 (2004), 741. The final goal is to obtain a credible evaluation of some key parameters such as efficiency and cross talk NEDA as multiplicity filter to select n-rich reaction channels NEDA meeting

  6. Light-output definition The light-output L is usually given in MeVee: the particle energy required to generate 1 MeVee of light is defined as 1 MeV for fast electrons e- @ 1 MeV Light: 1MeVee PMT e- range L is generally less for heavier particles such as protons, deuterons, alphas, beryllium, carbon… Therefore, the light output L in a certain path dx is a function of the deposited energy E in dx: L(E) NEDA meeting

  7. Light-output estimation The Birks-Chou formula provides a theoretical description of the light emission However, an easier phenomenological formula is also available E - ΔE ΔL = light output of the particle scattered by a neutron in a single ith step of its stopping process E NEDA meeting

  8. Light output parametrization (1) Dekempeneer et Liskien NIM A 256 (1987) 489-498: NE213 The light-output function provided for protons is a polynomial one (3rd order ) : LP(E)=A0+A1E+A2E2+A3E3 Carbon, Boron: L(E) = 0.0097 E Deuteron: L(E) = 2 Lp(E/2) Be: L(E) = 0.013E • 0.0201E1.871 E < 6.76 MeV • -0.6278+0.1994 E E ≥ 6.76 MeV Alpha: L(E) = NEDA meeting

  9. Light output parametrization (2) Many parameterizations exist in literature, also for energies above 16 MeV. R.A. Cecil et al. NIM 161 (1979) 439-447, for example N.P. Hawks et al., NIM A 476 (2002) 190 D. Cano-Ott and collaborators, private comm. NEDA meeting

  10. Light output parametrization (3) µ = 0.045 β = 0.075 Y = 0.002 Gaussian resolution for L H. Schölermann and H. Klein, NIM 169 (1980), 25 The resolution describes: Light transmission from different points (µ)‏ Statistical effects on light production (β)‏ Noise (Y)‏ NEDA meeting

  11. Light output for 10 MeV neutrons(electrons) Light output Deposited energy 10* keV 10 * keVee 16/06/2009 NEDA meeting 11

  12. Light output for 10 MeV neutrons(protons) Deposited energy Light output 10 * keV 10 * keVee NEDA meeting

  13. Light output for 10 MeV neutrons(carbon) Deposited energy Light output 10 * keV 10 * keVee NEDA meeting

  14. Light output for 10 MeV neutrons(alphas from 12C+n->9Be+4He) Light output Deposited energy 10 * keV 10 * keVee NEDA meeting

  15. Light output for 10 MeV neutrons(9Be from 12C+n->9Be+4He) Light output Deposited energy 10 * keV 10 * keVee NEDA meeting

  16. Light output for 10 MeV neutrons(deuterons) Light output Deposited energy 10 * keV 10 * keVee NEDA meeting

  17. Light output for 10 MeV neutrons(photons) Light output Deposited energy 10 keV 10 keVee 16/06/2009 NEDA meeting 17

  18. Light output for 10 MeV neutrons(all) Light output Deposited energy 10 * keV 10 * keVee NEDA meeting

  19. Efficiency The efficiency of the NEDA prototype is calculated for an emission at 1m distance with an angular aperture of θ =17° θ Tayfun Huyuk, private comm. source 1 m The efficiency has been calculated for 4 different thresholds as: NEDA meeting

  20. Threshold (MeVee)‏ Efficiency % 0 74.6 0.25 6.5 0.50 6.0 0.75 5.5 Threshold (MeVee)‏ Efficiency % 0 63.6 0.25 40.1 0.50 36.2 0.75 33.1 Efficiency: results 1 MeV n 0.75 0.50 0.25 10 keVee 8 MeV n 0.25 0.75 0.50 10 keVee 16/06/2009 NEDA meeting 20

  21. Cross talk Cross talk: the same neutron can be scattered and detected among different scintillators n' Cross talk: n Tayfun Huyuk, private comm. We calculated it for 19 detectors, in the same conditions as the efficiency simulation NEDA meeting

  22. Cross talk: results 1 MeV n 0.75 0.50 0.25 10 keVee 8 MeV n 0.25 0.75 0.50 10 keVee NEDA meeting

  23. Conclusions and open problems We have implemented in Narray code the calculations for the light output of a scintillator, considering the different kinds of recoils involved. HOWEVER… • What parameterization to be used? Several available, situation more confused for energies above 16 MeV 2. Is the light-output really a universal function? 3. Need to test the scintillator to validate simulations? NEDA meeting

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