Quantum efficiency for photosensors

In the geant-based simulation of GlueX DIRC we assumed the Hamamatsu H8500 photosensors.

For GlueX experiment they are going to be multialkali H12700.

Here the detailes about the quantum efficiency (QE) for both models of MCP-PMTs are collected. To produce the QE tables, the dependency of the quantum efficiency on the wavelength was extracted from the data sheet and fitted. 

H8500 H12700
data sheet data sheet
QE table

QE table

 

 

 

 

 

 

 

 

 

 

 

 

Photon detection efficiency (PDE) describes detecting a photon after is arrives at the detector plane. PDE consists of the following factors:

  • fraction of the detector plane covered by the photosensitive area (photocathode), which depends on how close the PMTs are packed together and how much of the PMT front is covered by the photocathode, e.g. area ratio of the photocathode size to PMT size (open-area-ratio (Photonis terminology) or packing density (Hamamatsu terminology))
  • probability, that the incident photon generates a photoelectron (quantum efficiency (QE))
  • probability, that the photoelectron starts the electron amplification (collection efficiency (CE))

QE*CE as a function of photon wavelength and energy for different photosensors (CE = 0.65 for Planacon MCP-PMTs and close to 1 for Hamamatsu MaPMTs): 

green - measurements for Photonis XP85112 (A.Britting), which is currently used in the Geant simulation

blue and black - data for Hamamatsu devices H8500 and H12700 respectively (taken from the data sheets and adapted by C.Fanelli)

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Currently we have the following photocathodes (most of them might be really old) in the simulation:
1. Burle
2. some hamamatsu model (according to comments)
3. H12700
4. Planacon, data from Alex Britting (2011)
QE for these photocathodes is shown on the following plot. To get the detection efficiency for one pixel, QE should be multiplied by the corresponding CE (see in the legend for the right plot).