LIGHT-OUTPUT SIMULATIONS FOR NEDA Andrea Gottardo Università di Padova
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Transcript of LIGHT-OUTPUT SIMULATIONS FOR NEDA Andrea Gottardo Università di Padova
LIGHT-OUTPUT SIMULATIONS FOR NEDA
Andrea Gottardo
Università di Padova
“Universa Universis Patavina Libertas”
20/04/23 1NEDA meeting
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
20/04/23 2NEDA meeting
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.
electronics
PMTlightNeutron
Scintillatorcharge
Neutrons with the same energy do not always produce the same light output, i.e. the same signal intensity
20/04/23 3NEDA meeting
Scintillator light response
The light-response depends on:
• 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…
20/04/23 4NEDA meeting
Light-output importance for NEDA
Simulation for neutron detectorRealistic estimation of the intensity of output signals
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
20/04/23 5NEDA meeting
Light-output definitionThe 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
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)
e- @ 1 MeV PMTLight: 1MeVee
e- range
20/04/23 6NEDA meeting
Light-output estimation
The Birks-Chou formula provides a theoretical description of the light emission
However, an easier phenomenological formula is also available
ΔL = light output of the particle scattered by a neutron in a single ith step of its stopping process E
E - ΔE
i
iLL
12
1
dx
dEC
dx
dEkB
dx
dES
dx
dL
20/04/23 7NEDA meeting
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)
Alpha: L(E) = •0.0201E1.871 E < 6.76 MeV•-0.6278+0.1994 E E ≥ 6.76 MeV
Be: L(E) = 0.013E
20/04/23 8NEDA meeting
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
20/04/23 9NEDA meeting
N.P. Hawks et al., NIM A 476 (2002) 190
D. Cano-Ott and collaborators, private comm.
Light output parametrization (3)
Gaussian resolution for L2222 Y+Lβ+LμFWMH
µ = 0.045
β = 0.075
Y = 0.002H. Schölermann and H. Klein, NIM 169 (1980), 25
The resolution describes:
1. Light transmission from different points (µ)
2. Statistical effects on light production (β)
3. Noise (Y)
20/04/23 10NEDA meeting
Light output for 10 MeV neutrons(electrons)
Deposited energy Light output
10* keV 10 * keVee16/06/2009 11NEDA meeting20/04/23 11NEDA meeting
Light output for 10 MeV neutrons(protons)
Deposited energy Light output
10 * keV 10 * keVee20/04/23 12NEDA meeting
Light output for 10 MeV neutrons(carbon)
Deposited energy Light output
10 * keV 10 * keVee20/04/23 13NEDA meeting
Light output for 10 MeV neutrons(alphas from 12C+n->9Be+4He)
Deposited energy Light output
10 * keV 10 * keVee20/04/23 14NEDA meeting
Light output for 10 MeV neutrons(9Be from 12C+n->9Be+4He)
Deposited energy Light output
10 * keV 10 * keVee20/04/23 15NEDA meeting
Light output for 10 MeV neutrons(deuterons)
Deposited energy Light output
10 * keV 10 * keVee20/04/23 16NEDA meeting
Light output for 10 MeV neutrons(all)
Deposited energy Light output
10 * keV 10 * keVee20/04/23 17NEDA meeting
EfficiencyThe efficiency of the NEDA prototype is calculated for an emission at 1m distance with an angular aperture of θ =14°
20/04/23 18NEDA meeting
θ
1 m
source
The efficiency has been calculated for 4 different thresholds as:
sentN
Neff 1
Tayfun Huyuk,
private comm.
16/06/2009 NEDA meeting 19
Efficiency: resultsThreshold
(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
10 keVee
10 keVee
1 MeV n
8 MeV n
0.75
0.25
0.50
0.25
0.50
0.75
20/04/23 19NEDA meeting
Cross talk
n
n'
Cross talk: the same neutron can be scattered and detected among different scintillators
hit
hits
N
N
1
2Cross talk:
We calculated it for 19 detectors, in the same conditions as the efficiency simulation
20/04/23 20NEDA meeting
Tayfun Huyuk,
private comm.
Threshold (MeVee)
Cross talk%
0 46.8
0.25 16.2
0.50 8.7
0.75 3.8
Threshold (MeVee)
Cross talk%
0 39.4
0.25 17.6
0.50 12.0
0.75 8.3
20/04/23 21NEDA meeting
10 keVee
10 keVee
0.75
0.25
0.50
0.25
0.50
0.75
1 MeV n
8 MeV n
Cross talk: results
Conclusions and open problems
1. What parameterization to be used?
2. Is the light-output really a universal function?
3. Need to test the scintillator to validate simulations?
20/04/23 22NEDA meeting
Several available, situation more confused for energies above 16 MeV
We have implemented in Narray code the calculations for the light output of a scintillator, considering the different kinds of recoils involved.
HOWEVER…
Light output for 10 MeV neutrons(photons)
Deposited energy Light output
10 keV 10 keVee16/06/2009 23NEDA meeting20/04/23 23NEDA meeting