Non-ionizing energy loss changing between Geant4 versions

Dear expert,

We have questions regarding non-ionizing energy loss (NIEL) responses from different Geant4 versions. We are studying low energy nuclear recoils in the context of direct dark matter searches. Due to the complexity of our application, we used TestEm7 to demonstrate the discrepancies among the NIEL outputs we found when comparing different versions of Geant4. These follow below:

Alphas in G4_WATER using TestEm7 for different Geant4 versions

NIEL (keV)
Projectile Energy / Geant4 version 9.04.p04 10.01 10.06.p02
400 MeV 44.0302 41.3047 37.4116
1 MeV 4.92809 4.05593 3.22313
100 keV 3.95646 3.25450 2.50133
10 keV 2.11553 1.74585 1.17265
1 keV 0.56217 0.49206 0

We would like to point out that we used the standard electronic energy loss and the G4ScreenedNuclearRecoil for the nuclear part. Would it be possible for you to enlighten the reason for these significant discrepancies.

Thanks in advance.

PS: Follows attached the macro used on this study.

alpha.txt (559 Bytes)