The standard detector for the diffractometer in the experimental hutch 2 (EH2) is a 0-dim scintillator 1XMP040B from BICRON corporation The connection scheme is shown in figure:



The detector is mounted on the GamR circle on the detector arm of the horizontal six-circle diffractometer. It consists on a NaI(Tl) scintillator crystal followed by an AMPEREX XP-1010 photo-multiplier tube. The output of the photo-multiplier is fed to a preamplifier located in the same metallic container.

The output from the preamplifier is connected to the Ortec Model 590A amplifier and single-channel analyzer through the AMP IN bnc connector in the front panel. This electronic is located in the NIM crate (rack 08 in the control hutch). At the rear panel there is a DB9 female connector providing the electrical power for the detector preamplifier. The amplifier has a single output that can be switch-selected for either unipolar or bipolar pulse shape. A coarse gain switch and fine gain control select the gain factor for the amplifier. A switch selects the appropriate input polarity of pulses from the preamplifier. The shaping of the pulses is controlled by three pcb switches accessible through the side panel. The output window discriminator can be adjusted by means of two 10-turn potentiometer. The lower level discriminator potentiometer determines the lower level threshold between 0-10 V. When the lower level reference switch on the rear panel is in the Ext position the lower level control is disabled and discriminator bias is provided from the Ext LLD input connector. The window potentiometer determines the window level (0-10V) above of the lower level threshold. Associated with this potentiometer there is a switch selecting between integral operation (only lower level discriminator) or windowed operation. The AMP OUTPUT provides a positive unipolar or bipolar amplified output and the SCA OUTPUT provides a NIM standard output of +5V, 500ns wide.

In the same crate there is a High Voltage power supply Ortec Model 478 which provides the high voltage for the operation of the photo-multiplier tube. The high voltage output bnc connection is located in the rear panel of this electronics.

At the right side of this module there is a Ortec log/lin rate-meter Model 449 mainly used while looking for bulk Bragg peaks.

The recommended operation settings for the detector electronics are:

Ortec 478 High Voltage power supply:
Output Voltage 750V.
(black knob in the zero position and 7.5 in the dial of the ten turn potentiometer)

Ortec 590A Amplifier and timing single-channel analyzer:
Fine gain: 0.5
Coarse Gain: 10
(with these settings the energy calibration of the pulse height is ???? V/keV).
Pos-Neg switch: POS
Unipolar-bipolar switch: UNI.
Side panel pcb switches: S1, S3, S6 = 0.5 usec.
If a crystal analyzer is mounted before the detector:
    Window-integral switch: INT.
    Lower-level: 0.5-1.0 V