Difference between revisions of "D2O photodisintegration simulation"
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We have to be really careful about placing lead shielding around the beam line. Scattered photons may produce background neutrons in the lead shielding of neutron detectors. | We have to be really careful about placing lead shielding around the beam line. Scattered photons may produce background neutrons in the lead shielding of neutron detectors. | ||
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+ | The simulation shows that enrgy spectrum of photons that is seen by our neutron detectors has the following shape (initial brem spectrum modified by the <math>D_2O</math> target): | ||
[[File:Modified_brem.gif | 550 px]] | [[File:Modified_brem.gif | 550 px]] | ||
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+ | Hence, it seems that there is no need to worry about neutrons produced in the lead shielding of our neutron detectors because we do not have many photons being able to produce neutrons in the lead. | ||
==Neutron spectra separation== | ==Neutron spectra separation== |
Revision as of 15:03, 11 April 2011
reaction cross sections for different elements
The result of GEANT4 simulation of neutron photoproduction on deuterium and oxygen-16 is presented below:
Experimental cross section for
We have to be really careful about placing lead shielding around the beam line. Scattered photons may produce background neutrons in the lead shielding of neutron detectors.
The simulation shows that enrgy spectrum of photons that is seen by our neutron detectors has the following shape (initial brem spectrum modified by the
target):Hence, it seems that there is no need to worry about neutrons produced in the lead shielding of our neutron detectors because we do not have many photons being able to produce neutrons in the lead.
Neutron spectra separation
Neutron yield (
) from (90% concentration) in reaction is presented below. Initially brem photons with 25 MeV end-point energy were thrown on the target. 410 neutrons initially produced got absorbed in the target (E=0MeV) and 2509 neutrons will likely escape the target. Figure in blue on the left is the total energy spectrum of neutrons created in reaction . Figure in blue on the right is the neutron energy spectrum with energy cut applied.Neutron yield (
) from (90% concentration) in reaction is presented below. Initially brem photons with 25 MeV end-point energy were thrown on the target. 857 neutrons initially produced got absorbed in the target (E=0MeV) and 16799 neutrons will likely escape the target. Figure in black on the left is the total energy spectrum of neutrons created in reaction . Figure in blue on the right is the neutron energy spectrum with energy cut applied.So, if we apply the energy cut in neutron spectrum which is a sum of neutrons coming from
and reactions at (0MeV)<E<=5MeV, then the ratio of "unpolarized" neutrons from and "polarized" neutrons from will be . In the same time we will loose of the "good" high energy neutrons produced in reaction. Binning is the same for all the plots above.I will verify if those spectra and all the ratios are the same in the case where we use the geometrical constrains applied by the detectors placement.