agata demonstrator test with a 252 cf source: neutron-gamma discrimination
DESCRIPTION
AGATA Demonstrator Test With a 252 Cf Source: Neutron-Gamma Discrimination. Menekşe ŞENYİĞİT. Investigation the possibilities of discriminating neutrons and gamma rays are important ! Methods for neutron-gamma discrimination with tracking :. - PowerPoint PPT PresentationTRANSCRIPT
AGATA Demonstrator Test With a 252Cf Source: Neutron-
Gamma Discrimination
Menekşe ŞENYİĞİTMenekşe ŞENYİĞİT
Investigation the possibilities of discriminating neutrons and gamma rays are important !
Methods for neutron-gamma discrimination with tracking:
• The energy deposited in the first and second interaction points; • The difference in incoming direction of the gamma ray ;
• Selection based on the FM value
first secondandE E
E G
To check our methods, we consider an experiment with AGATA triple cluster , 252Cf source and BaF2 detector. BaF2 detector is used for timing. Test period is about 3-4 hours.
BaF2
Lead Shield
252Cf source60Co source
( cm3)
AGATA single cluster
Loss in gammas ~92-99%Loss in neutrons ~47-50%
Simulations1. Simulations Geant4 with
AGATA triple cluster
Cou
nts
Neutron Energy (MeV)
2. Simulated data: About 1 MeV -rays Neutrons emitted from 252Cf source
with 2.95 Ci (at LNL)
3. Tracking with MGT code
Gamma-ray energy spectrum after tracking (mgt)
EEγ (keV)γ (keV)
coun
tsco
unts
Neutrons emitted from 252Cf source with PHDEF Distance between lead shield and AGATA triple cluster is 60 cm
Number of events:35046000
Neutron multiplicity:4
Run time:3 hours
Tracking efficiency for gammas:0.97
EEγ (keV)γ (keV)
coun
tsco
unts
834 keV834 keVNo conditionsNo conditions
With conditionsWith conditions
Gamma-ray energy spectrum after tracking (mgt) * Neutrons emitted from 252Cf source with PHDEF and 1 MeV -rays
* Distance between lead shield and AGATA triple cluster is 60 cm
19854357θg – θc or Efirst or Esecond
or FM
11692646θg – θc or Efirst
145317 Efirst
10612543θg - θc
1 MeV gamma
bumppeak 834 keV
total834 keV, 72Ge834 keV, 72Ge
Time of Flight Spectra for 70 cm
TOF
Cou
nts
-rays
Neutrons
• In this experiment we would also like to use the TOF technique in order to know when a neutron is hitting detectors to check how succesful our methods are.
•One problem is that one don’t know the time resolution of the AGATA detectors.
•Without PSA, it may be around 10 ns but this may be reduced very much by the PSA.
•Time resolution is energy dependent.
Time ResolutionC
ount
s
Cou
nts
Cou
nts
TOF, Time resolution = 1 ns TOF, Time resolution = 3 ns TOF, Time resolution = 5 ns
Since we don’t know what the time resolution will be for AGATA detectors, we made TOF simulations by using different resolution values.
-rays Neutrons -rays
Neutrons-rays Neutrons
Cou
nts
TOF, Time resolution = 10 ns TOF, Time resolution = 15 nsC
ount
s
-rays Neutrons
-rays Neutrons
Conclusions
• We developed 3 methods for neutron-gamma discrimination by using tracking. We would like test these methods in a real test experiment where we shall use a 252Cf neutron source, one triple Agata detector and a BaF2 detector for timing.
• We made some simulation in order to check the effect of our methods.
• We checked the effect of different time resolution.
We are preparing a proposal for this test experiment which can be run just after the summer.