3.6. Card 5: Spallation and neutron irradiation options

Table 3.6.1 AMP PHITS: same name

Value	Description
(D=1.0, DP=automatically calculated [1], requires JMODE=0,2)	A factor to normalize activation by primary beam(particle mA). Please note that this factor is not applied to activation by secondary neutrons. When the source intensity is 1(source/s), the value is 1.6022E-16(particle mA) regardless of the source particle species.

Table 3.6.2 EBEAM PHITS: same name

Value	Description
(D=3.0, requires JMODE=0,2)	Primary beam energy in [GeV]. [2]

Table 3.6.3 PRODNP PHITS: same name

Value	Description
(D=1.0, requires JMODE=0,2)	Neutron yield per input primary beam. This option is used to calculate the neutron flux from neutron spectra in MCNP output (when FLUXS=-1) and thus is effectively deprecated.

[1]

AMP is calculated using the PHITS [T-Dchain] input parameter amp (inputted in source/second) multiplied by \(1.602177\times 10^{-16}\) mA/e. DCHAIN will automatically convert this back into particles/second by dividing AMP by \(1.602177\times 10^{-16}\). If simulating a beam with a charge other than \(\pm\)1 and manually manipulating the value of AMP in the DCHAIN input deck, please keep this conversion in mind. Additionally, DCHAIN’s AMP parameter has no influence on the neutron flux, which is set by FLUXS in each region; however, PHITS does calculate FLUXS using the amp parameter in [T-Dchain].

[2]

EBEAM is only used meaningfully if ITDECS=1 to calculate the spallation/destruction cross section of the target material from incident protons at EBEAM GeV using Pearlstein systematics [Pea87]. Note that this cross section is only used for reducing the beam flux as the target material is depleted, scaling down production of all other nuclides which originate from the target; the negative yields present in the *.dyld file generated by PHITS control the actual target nuclide depletion rates. Otherwise, EBEAM is only used to calculate beam power in MW displayed in the output files.