Cyberstar

The "Cyberstar" detector is used in the vertical axis diffractometer (experimental hutch 1, EH1) mounted on the diffractometer detector arm.

The scintillator used is a NaI(Tl) crystal providing a working energy range up to 50keV. The detector aperture is standard 32 mm diameter with a detector window in Beryllium of 0.2 mm thickness. After the scintillator there is a photo-multiplier tube with the photo-cathode adapted to the NaI(Tl) scintillation wavelength. The photo-multiplier has a typical gain of 10e6 providing an output pulse with rise time of 2.8 ns. Directly attached to the dynode chain there is a fast preamplifier.

In the back part of the detector housing there are a Lemo ERA size zero connector for the high voltage and an Anphenol 17DMW connector for the preamplifier power and signal output.

The control electronics Cybestar Model CS93PPU is located in a rack NIM in the rack 08 of the control hutch. This electronics integrates the high voltage power supply, the shaping amplifier and the single channel analyser. In the rear panel there is a DB9 female connector for the preamplifier power, a bnc for the signal input and a high voltage bnc for the photo-multiplier high voltage output. The unit is equipped with a serial line communication port configurable between RS232 or RS485. The DB9 male serial line connector is located in the rear panel.

The photo-multiplier voltage is adjustable between 250V and 1250V by means of a 10 turns potentiometer in the front panel. A 3 1/2 digit led display provides the reading of this voltage.

The amplifier gain can be continuously adjusted between 0 and 10 by a ten turn potentiometer located in the front panel. The shaping constant can be changed by a 4 position rotary switch.

The low level discriminator threshold and the upper level threshold are adjustable between 50 mV and 10V by two ten turns potentiometer in the front panel. A four positions rotary switch is used to change the operation mode of the window discriminator:

  -n normal:     Upper and lower level are separately adjustable
                 between 0 and 10V.
  -i Integral:   Upper level disabled.
  -a asymmetric: Upper level adjust between 0V and 1V the window above the
                 lower level.
  -s symmetric:  Upper level adjust symmetrically between 0.5V and -0.5V above
                 and below the lower level.

The amplified signal is present at the signal out bnc connector in the front panel. The discriminator output is a TTL or negative current fast Nim logic level jumped selected in the printed circuit board. The out put signal is accessible at the window out bnc output in the front panel.

The control unit can be remote controlled through the communication port. To use this feature the local-remote switch in the front panel must be set to remote (red light on). From this moment the control unit can be controlled only by the control program (spec, etc...). This option is not currently available.

The recommended operation settings are:

• High Voltage: 1000 V
• Gain : 5
• Peaking time: 0.5 - 1 usec.
• TTL Fast NIM: TTL
• if an analyzer system is mounted
  • Discriminator mode: Integral (i)
  • Lower level: 0.5 - 1 V