diff --git a/xray/utils.py b/xray/utils.py
index 864d844..d1f2efa 100644
--- a/xray/utils.py
+++ b/xray/utils.py
@@ -305,7 +305,7 @@ def transmission(material='Si',thickness=100e-6, density=None, natural_density=N
   return np.exp(-thickness/att_len)
 
 
-def chargeToPhoton(chargeOrCurrent,material="Si",thickness=100e-6,energy=10,e_hole_pair=3.6):
+def chargeToPhoton(chargeOrCurrent,material="Si",thickness=100e-6,energy=10,e_hole_pair=3.63):
   """
     Function to convert charge (or current to number of photons (or number 
     of photons per second)
@@ -322,8 +322,8 @@ def chargeToPhoton(chargeOrCurrent,material="Si",thickness=100e-6,energy=10,e_ho
   A = 1-transmission(material=material,energy=energy,thickness=thickness)
   chargeOrCurrent = chargeOrCurrent/A
 
-  e_hole_pair_energy = 3.6e-3
-  n_charge_per_photon = energy/e_hole_pair_energy
+  e_hole_pair_energy_keV = e_hole_pair*1e-3
+  n_charge_per_photon = energy/e_hole_pair_energy_keV
   # convert to Q
   charge_per_photon = n_charge_per_photon*1.60217662e-19
   nphoton = chargeOrCurrent/charge_per_photon