Maximum Voltage Measurements of the ORB's prompt output (to be completed)

In order to measure the maximum voltage prompt output of the ORB modules, I used the following set up: a waveform generator (in mapo there is a HP WF generator up to 15 MHz), the UCI laser diode, a TTI optical-electrical converter, a good optical fiber, some lemo cables. First one has to calibrate the generated optical pulse, to do this one has to plug in the output of the WF generator directly to the BNC input of the laser diode, which needs to be plugged into the power. To get a similar PMT pulse, one can generate pulse with 10MHz frequency so to get a pulse width of the order of 100 nsec. The laser diode has an optical output which can be connected to the TTI optical-electrical converter in order to test the produced pulse. The electrical output of the TTI converter can be plugged into an oscilloscope so to adjust a desired pulse. There are two methods for changing the amplitude of the generated pulse. One from the pulse amplitude of the WF generator and the other from the UCI laser diode. However to have an idea of the given amplitude it is better to adjust the amplitude pulse from the generator. Applying different voltage from the generator up to 5 Volt I could see on the oscilloscope a saturation value output from the laser diode of 1.80 V. After testing the pulse on the scope, one can directly plug the output of the laser diode by means the optical fiber to the input of the ORB. From the prompt output of the ORB one can check on the oscilloscope the resulting pulse, changing amplitude one can see easily the saturation of the ORB channel. I tested randomly some prompt output of different ORB modules, unfortunately I did not have time enough to check all ORB channels. I summarize here below the channels measured. Starting from the left ORB close to the DOM DAQ I used the following convention ORB Module 01, ORB Module 02,...


ORB Module 01

17-12 0.98 17-15 1.08 17-19 0.96 17-20 1.08 17-21 1.05 17-23 0.97

ORB Module 02

17-03 1.13 17-30 1.13

ORB Module 03

18-03 1.06 18-05 0.70 18-10 0.71

ORB Module 04

18-31 0.91 18-16 1.08

ORB Module 05

18-23 1.16 18-25 0.87

ORB Module 06

18-33 0.91 18-37 1.08

ORB Module 07

19-04 1.28 19-05 1.05

ORB Module 08

19-11 1.17 19-13 1.14

ORB Module 09

19-22 1.09 19-24 1.09

ORB Module 10

17-37 1.17 17-38 1.12

ORB Module 11

14-01 0.77 14-04 1.05

ORB Module 12

14-11 0.74 14-13 1.04

ORB Module 13

14-21 1.20 14-23 0.99

ORB Module 14

14-34 1.11 14-38 1.12


Andrea Silvestri
Last modified: Sat Jan 4 04:00:00 GMT 2003