Beam Test H8, Sep. 95

Author: Wilko
This page was created October 5, 1995, last modified November 28, 1995


  1. Introduction
  2. Tested Detectors
  3. Runs
  4. Calibration
    1. Tested Detectors

      During the September beam test (20. Sep - 27. Sep) five detectors were tested.

      A double sided n-bulk strip detector. Pitch 50 µm. The front end consisted out of the LBIC, CDP128 and a HAC chip. Five CDP128 were read out. The p-side of the detector was not read out.
      2 CDP128 chips.
      lbl_lbic1_0, lbl_lbic1_1
      For the lbl_lbic1 two n-bulk, p-side detectors are glued back to back. The strip length is 12 cm, the pitch is 75 µm. Six CDP128 were read out connected to 12 LBIC preamp.
      The oxford_ddr2 uses a different digital read out. The ddr2 chip is a data driven digital chip. As preamp, comparator chip the LBIC was used. A 6 cm double side strip detector was used (from Hamamatsu). Only the p-side was connected to the front end electronics. 640 channels (five ddr2 chips) were read out.


      In the september beam test three main test programs were performed.
      • Threshold scans for different bias voltage for the ucsc and ddr2 module.
      • Threshold Scans for different angles (0°, -7°, -14°) for the lbl_lbic1 and lbl_att3 modules.
      • Noise occupancy for various threshold setting (random trigger).
      A list of all the runs are found in: The run configuration files and threshold files (binaryConfigacX.X, bcX.X, rcX.X).

      Bias voltage scans for ucsc and ddr2

      Angular scans for lbl_att3 and lbl_lbic1

      The ucsc_1_n and the oxford_ddr2 were used as anchor planes and the the detectors, lbl_lbic1 and lbl_att3, were installed in the movable/rotation stage.

      • slot 1b: ucsc_1_n
      • slot 2a: lbl_att3
      • slot 2b: lbl_lbic1
      • slot 3a: oxford_ddr2

      Compared to the bias voltage scan, which was done before, the modules were rotated by 180°.

                   ----------------|------------------    detector 
                   ----------------|------------------    strips.
                                   | <--- rotation axis
                                /  beam 

      Random trigger

      With a random trigger the noise occupancy for various threshold settings was measured. The threshold was varied between 0.3 fC and 1.2 fC. At 1.0 and 1.2 fC 50K triggers were collected, otherwise 2 - 5K's.


      The binary readout is calibrated by injecting charge into the input of an amplifier and measuring the efficiency versus the threshold value. The threshold where the efficiency is 50% i.e. the median, is called the response of the amplifier for that particular input charge. The response for various input charges is measured and a response function is fitted to these points. By this way a relation between the threshold, set in mV,

      The table SCIPP Silicon or ATLAS-Silicon.