Radiation hardness, excess noise factor and short-term gain instability of vacuum phototriodes for the operation in pseudorapidity range 1.5⩽η⩽3.0 at CMS ECAL

Abstract The operation of super radiation hard prototypes of vacuum fine-mesh phototriodes (VPT) proposed for application in CMS Endcap ECAL at the pseudorapidity of η ⩾2.6 has been investigated in radiation fields up to 50 kGy and neutron fluence of 7×10 15  neutron cm −2 . It is shown that anode response and the excess noise factor of VPT are independent of given above radiation dose and neutron fluence. The results of VPT gain variation measurements under rapid changes of counting rate are presented for the operation in the pseudorapidity range 1.5⩽ η ⩽3.0.