Welcome to the 
TAMU MINOS work area

Measurements of Z Positions of Planes

Here are the links to the measurements of the Z-positions of the face of the steel plates near the axial bolts at the far detector. If you have any questions about these measurements please let me know.

Z positions of the planes

Differences between average Z

Plane Checkout Procedures

Here is the latest version of the plane checkout QC sheet. At this time there is a single set of sheets outlining the procedures done both horizontally and vertically. This is the form as it was modified following the Installation Workshop at Tower on 10/13-14/2001.

planeqc1022.doc

LeCroy 1440 HV system parameters for MINOS detector operation

Below you will find figures referencing several sets of measurements that we made on a LeCroy 1440 here at TAMU. These measurements were made using a phototube base drawing 0.5 mA of current on the output being tested. This is similar to the load that we will be using on the M16 base planned for the far detector.

HV limit setting performance

This figure show the effect of the hardware HV limit setting on the voltage being delivered to the base. Measurements were taken with three values of the HV limit setting; 0.3, 0.35 and 0.4. At each setting we then ramped the requested voltages up in steps and "measured" the voltage detected on the output with a DVM. We saw that at the 0.3 setting we could get to an output voltage of 1000 volts but this required asking the supply to put out a voltage of 1200 volts or so to reach this level. If we have tubes that will require operating at the HV limit of 1000 volts we will either have to operate the system with a slightly higher HV limit like 0.35 or be prepared to allow for demand voltages higher than 1000 volts to be accepted and processed by the DCS system.

HV limiting using current limit settings

This figure shows the measured output voltage as a function of the current limit setting of the 1440 system. To make these measurements, we fixed the requested voltage at 1000V\ and then changed the current limit from 0 - 256 and at each current limit setting we measured the voltage being delivered to the test base. In this figure we display the voltages measured by DVM as well as the voltages readback by the 1440 system itself.

HV limit setting performance

In this figure, we carry out the same measurements as described in the paragraph above. However this time the figure displays two different fixed values of the requested output voltage and the response to the system while varying the current limit setting.

From these two sets of measurements it looks like the 1440 systems should be run with the hardware HV limit set at between 0.3 and 0.35 AND for an extra measure of protection we should probably set the current limit to be in the range of 100-125.

Cross talk measurements on 2 M16s (New and Old)

Below you will find figures referencing the cross-talk measurements that we have made here at TAMU. In the case of the Old M16, we saw that there were some curious cross-talk patterns in the tube when certain pixels were illuminated. An example of this is shown in the ADC spectra for the 16 pixels when pixel 6 is illuminated. All of the surrounding cells clearly show a single photoelectron peak, and cell 14 has many more hits than cell 4.

Old M16 cross-talk

We performed similar measurements on a newer MINOS M16(SN # 9H25C2) and saw a much nicer behavior. When illuminating pixel 6 in this tube we saw that the cross-talk was independent of the illumination of the primary pixel and that there were no anomalous pixels. At 800 V we measured the cross-talk and found that it was hard to see whether the cross-talk signals were really 1 pe or a continuous charge distribution, see

Cross-talk at low gain.

To investigate this further, we took the same set of data at a voltage of 1000 V to see if we could see nice pe distributions. The results of these measurements are shown in

Cross-talk at high gain.

In this plot you can clearly see that the signals in the cross-talk pixels show strong evidence of a 1 pe peak. Lastly, we summarized these measurements over the full range of illuminations in

the cross-talk versus illumination figure.

In our cross-talk measurements on these M16s we saw no illumination dependences of the cros-talk and the newer M16 had a

cross-talk pattern

as shown in the figure. In this plot the vertical bars represent the cross-talk measured for that particular pixel as a percentage of the light detected in the primary pixel. Each of these groups represents an illumination at a different number of primary pes.