The work of this group falls into two distinct areas, tests on individual components and tests on these components as a subsystem in a full system.

Components

The individual components comprise

1) VECSELS

2) PIN Diodes

3) DORIC Chips

4) VDC Chips

5) Fibres

6) Opto Package

7) Plug-in Assembly (plug-in)

Items 1) – 6) have already been evaluated extensively by the links group as individual components and, for the purposes of the PRR, it is thought that references can simply be made to this work.

At the time of the PRR, it is likely that there will not yet have been a final decision on which of the two possible options (GEC or Taiwan) for item 6), the Opto package, will be used, but information will be available for both options.

Note that the active components will be the same in both and that the difference is essentially one of different package design and assembly techniques.

Item 7) the plug in assembly is the only component that is unique to the forward modules.

The final form of this will depend on the final choice of opto package. The difference between the two types is simply that, should the Taiwan package be chosen, because this already uses a PCB substrate to mount the active components, then it may be possible to attach the connector directly to this PCB rather than use an additional separate PCB as is required with the GEC package.

******* New one piece plug-ins produced in Taiwan.

Essentially the function and performance would be identical but the complexity and size would be reduced.

Prototypes of the plug-in have been assembled and are undergoing tests in the system test with more being assembled into a harness.

It was decided that the plug-n was a sufficiently different component to the bare Opto package that a sample should be irradiated with gammas and neutrons and its performance evaluated. N.B.the heavy metal content of the connector (brass nickel, gold), PCB (copper) and solder, mean that it is not possible to use the reactor facility at Ljubljana if we ever want them back. AW will contact Alex Grillo to see if this is possible in California.

====>>> ACTION AW - irradiate at least one plug-in for early Feb 01

******* ARRANGED FOR Taiwan packages END OF FEB

Already have test results from GEC packages on Barrel dogleg

Do not intend to repeat for forward. --- is this OK?

Performance as a subsystem.

1) Basic function testing

2) Bit Error Rate (BER)

3) Crosstalk (Xtalk)

4) Thermal

5) Mechanical and handling

Item 1) basic function testing, is essentially a check that the opto subsystem when implemented on the hybrid is able to drive the front-end chips after irradiation. As the hybrids can be driven electrically through the bypass inputs and read out via the spy outputs, it should be simple to identify any differences in performance attributable to the optical subsystem. Irradiated modules are now available to allow these tests to be made. However, whilst there were DORIC and VDC chips glued to the module during the irradiation they were not bonded and therefore not powered at the time. It was felt that, although for completeness it would have been preferable that the chips be powered, the results from individual irradiations of the components would be sufficient to make this unnecessary.

====>>> ACTION TS check opto and electrical performance are the same – ongoing in system test – will chase cumulative experience over next 2 months

******** No problems reported so far

Items 2) and 3) Bit error rate and crosstalk are standard test applied to the opto subsystem and data is available from the links group on individual components. The main difference between the forward and barrel implementations of the opto subsystems is that the forward has a slightly longer electrical path length and is thus slightly more prone to noise pickup and crosstalk. Tests on non irradiated, early versions of forward hybrids showed that the performance was within the specification for both tests. These tests will now be repeated with the irradiated modules.

=====>>> ACTION - AW, PWP, BER and Xtalk tests on irradiated module on RAL test setup - next few weeks

******** NOT DONE AW contacted – will set up

Item 4) Thermal performance. As the forward opto parts are mounted on the hybrid the temperature of these is directly dependent on the overall thermal performance of the hybrid. There are component lifetime considerations here. A thermal analysis was originally done some time ago, however since then there have been a number of changes made to the hybrid design, and the power dissipation estimates of the front end chips have risen. It is clear that this analysis must be redone and actual measurements made for the PRR

=====>>> ACTION - TS, Tim Jones -- calculation

- JP, Tim Jones -- thermal camera measurements?? in the next few weeks

-

********* Some preliminary camera measurements done. Camera not in systest any more.

Item 5) Mechanical. performance. The opto plug-in and fibres are small and fiddly and we need to verify that it is possible to safely handle, attach and dismount them, assess the likelihood of failure and iterate the design as necessary.

======>>>ACTION - JP will collect experience from system test over next 3 months

********* ONGOING

INFORMATION EXCHANGE - TS will set up web page to point to relevant material.

********* NOT DONE