Kinetic energy definition for heavy ions

Source Definition
1

Versions

FLUKA: 4-5.2
Flair: 3.4-5.4

Description

My ultimate goal is to sample the kinetic energy of a heavy ion from a table containing values in GeV/u.

Just for a sanity check, I wanted to recreate the kinetic energy of this ion, with 0.2 GeV/u input

flukainput
flukainput634×108 12.7 KB

My naive assumption was that I merely have to multiply 2.0D-01 (the energy value in GeV/u) with the relative nuclear mass of the ions, which should be the mass/u. However, when I write

*  |  Kinetic energy of the particle (GeV)
         TKEFLK (NPFLKA) = SQRT ( PBEAM**2 + AM (IONID)**2 )
     &                   - AM (IONID)
         E_REF = 2.0D-01 * AM (IONID) / AMUGEV
         write(LUNOUT,*) 'DEBUG: E = ', TKEFLK (NPFLKA), ', E_REF = ', E_REF

in my source.f file, I get the output

 DEBUG: E =    47.613270143553365      , E_REF =    47.600214721804427

so kinetic energy (E=TKEFLK) and what I calculated from the mass (E_REF) is not exactly the same. What is happening here? Is TKEFLK derived from a different mass than AM (IONID)?

Best regards
Roman

2

No (actually, AM (IONID) appears in the TKEFLK (NPFLKA) expression).

E_REF should read

E_REF = 2.0D-01 * AM (IONID) / AMUC12

since the input energy is intended per nuclear mass unit (and not atomic mass unit).