PMT housing and TL sample heating assembly :
This unit has a low dark current photomultiplier Tube generally of Hamamatsu / ET make, is used. However, assembly facilitates one to go in for other photomultiplier Tubes also with appropriate modification in the PMT socket wiring.
The cylindrical shell containing the Photomultiplier is fitted on to a rectangular base drawer block containing a heater arrangement and thermocouple, heater rods, connected to a power transformer.
PMT used is, of 11 dynode 29mm, low dark current PMT of ET enterprises make.
Dark current at 20°c = 0.2nA Max. cathode to anode voltage = 2000V.
Heating Arrangement: Resistive heating method.
Heating Element: (Heater Strip)
Kanthal strip (72% Fe, 23% Al and 2% Cr or Nichrome) is used as a heating element. Kanthal Strip has a circular depression of 14mm to hold discs and powder samples. Additional flat heater strips can be provided on request.
Heating Process: Programmed heating can be done in two modes: "PROG MODE" of Temp. controller through personal computer program. "ISO MODE" (Internal mode) of Temperature Controller, by varying the ten turn dial.
Thermocouple Sensor (Cr-Al spotwelded to heater strip).
High voltage to PMT:
A continuously adjustable HV (0- 1500V) @1mA is generated by HV circuits. User can select desired HV from front panel. There is HV socket (test) for checking HV presence on rear panel.
Auto-Ranging: Current output from the photomultiplier is taken to IF converter, to give frequency output proportional to PMT current. This wide dynamic range is achieved for plotting TL intensity on Y-axis.
From room temperature upto 500°c, in linear, plateau heating (One / Two / Three) modes of heating can be programmed.
Heating Rates: Heater strip can be programmed to heat the sample from 10°c / sec upto 40°c / sec and a max set temperature (allowed) is 500°c.
Arrangement for Optical Filters : One Heat absorbing glass / filter (IR cutoff filter): This is essentially an IR cut-off filter which allows only visible light and cuts off IR Radiation has been provided just below the PMT window. Additionally filters (Band pass) if required by the user may be positioned above the slot provided on the heater strip in the drawer assembly.
Nitrogen Flushing Nozzle: Nitrogen gas flushing (sent through a flexible rubber pipe), suppreses spurious luminescence from oxidation effects & combustion phenomena has been provided, on the rear panel side.
Dimensions of Integral unit:
25.5W X 26ht. X 48D in mm.