Detector

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The npdγ detector consists of 48 CsI(Tl) crystals arranged in 4 rings of 12 crystals each. Here is the current status update.


What's Done
The hardware is in place 15/04/08
LabView Control Moves table correctly 16/06/08
Encoder Noise acceptable. 18/06/08
Draft summary 19/06/08
What's Next
Baseplate to utk for machining.
Height adjust to be completed once table is installed in the cave.

Contents

UNDER CONSTRUCTION!

Recent Work

08_06_19 -- previous work has been undone and the baseplate is ready to be moved (ground still attatched), first draft of summary is posted, waiting for the art and grammar/spell check

08_06_17 -- Noise check complete see file: Noise Check. Please do not complain about lack of axis lables, i'm already there.

08_06_16 -- Ok, r10 error fixed motors work properly on to noise check.

08_06_10 -- W,X,Z systems work properly; Y axis has r10 error (we confirmed that Y motors and cables work)

08_06_10 -- loose wire on Z-axis, now Z-axis works properly

08_06_10 -- X-axis and W-axis function normally obey limit switch behavior. Y-axis and Z-axis wonky.

08_06_06 -- All of the limit switches are now communicating with the computer but there is a problem with their signal reaching the servo controllors. At the moment the motors may move even when the limit switch is tripped. We suspect a loose connection and anticipate this problem being cleared up shortly.

Status

After the DAQ was finished being debugged (@20Hz), attention was turned towards looking at some noise data, with and without LEDs. Two of the detectors have saturated signals regardless of whether the LEDs are on or not. Changing the gain on the triumf modules didn't seem to do much, which is when it was discovered that the signal cable from detector XX didn't necessarily go into slot XX on the sum/difference amplifier. After recabling, the always saturated detectors are 00 and 05. In comparison to preamps in the other detectors, which draw 90-110mA of current at 5V, these only drew 10mA and 60mA, respectively.

After checking the cables, the detector housing was opened and preamplifier boards removed. The DC-DC converter chips on both were checked and while 5V went into it, only about 2V came out, instead of the requisite 15V. Scott has ordered more DC-DC chips and replacement boards to be made.

Stand

The Detector frame rests on a table during the run. Currently the table has been asembled for diagnostic testing and will then be moved to the SNS once the cave is ready. Assosciated with the table are a series of motors to adjust the position of the table as well as a sensor package to report the location. These systems are connected to a electronics rack and then relayed to a computer. The system is controlled through lab view software. There is a beam height variance between Los Alamos and the SNS so an additional plate is being produced to accomodate the new beam height. The base plate will also be cut into two pieces; one piece for the detector, the other for the target.

Table Parts List

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Servostar Manual .

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Electronics Rack

Servo amps on top of rack

The rack houses the 4 Kollmorgen Motor Amplifiers and their power supplies (24V). All of the connections from these devices are wired to a black box in the rear of the rack. This box puts out a serial connection to the galil. At the moment the galil is sitting on the table next to the computer. .

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Computer

Motor Control GUI

The detector stand controller computer is up and running. The LabView Gui loads but at the moment it's commands are not executed by all the motors. The X and W motors respond properly however the Y and Z motors are non responsive. Currently we are trying to locate the manual for the controllers to interpered their led display.

Amp noise comparison Blue is the current signal

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Motionlink noise documentation

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Motionlink Variable & Command Reference .

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CsI Array Package

Looking Downstream
The package is currently assembled in the detector lab and is awaiting a noise measurement. See DAQ for more information and timeframe.

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CsI(Tl) Crystals

Crystal w/ Al housing

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Vacuum Photodiodes

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Preamplifier Boards

Circuit Diagram

Preamplifier

Preamp documentation Some of these boards do not work properly, NF will update on this.

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