July 2002

In this document we quickly summarize the risks of the EMTiming project and our plans. The primary design consideration (other than cost and physics motivation) for this system is risk. For this reason we have made the entire system connectorized so it can be disassembled quickly (approx 1 day) such that the detector is easily returned to its pre-modified state. This effectively minimizes the risk. Thus, we are covered for the unlikely case where the design doesn't work, or somehow compromises the existing system, or the case if part of the project is uncompleted. We have also chosen to only use off the shelf parts and simple construction techniques, and re-used parts or designs. This minimizes the risk of large cost overruns, schedule delays and technical and scope risks. Here we have tried to identify the risks, both in terms of the things which easily fit into the resource loaded schedule, and those which transcend boundaries and are not easily put into that scheme.

Specific questions:

Q: What if, after installation, the system interferes with the operation of the CEM?

A: If the system is determined to be interfering it can be disconnected quickly (~1 day) and the detector returned to pre-installation running conditions until the problem is corrected. It can then easily be re-connected.

Q: What if the project is late in installation?

A: Currently the project is not on the critical path for installation. If the project is late, we will not slow down the rest of the Run IIb installation as we do not need the detector to be rolled out for installation (other than 40 cables). Thus, there should be no need to wait for us to install. It will be incumbent upon us to finish during other shutdown times. Our system is completely connectorized so that the entire system may be decoupled from the rest of the detector with a day's worth of work and we will install when available and not interfere in the meantime.

Q: What is the risk of injuring the detector during installation?

A: Our primary installation on the detector is laying cables (the splitters) from the EM phototubes to the readout crates and we plan to have professionals (Dervin Allen etc. has agreed to help) helping us with the installation and the dressing. As they have done this many times before this should minimize any potential risks. The other cable installation is from the racks upstairs. Again this is done under the supervision of professional FNAL technicians. The installation of the Transition Boards and ASD is simply plugging in the boards downstairs as is standard operating procedure for the current HADTDC system. The remaining work is upstairs where installation issues are smaller.

Q: What if the splitters affect the readout of the CEM?

A: Every attempt will be made to minimize the impact of the splitter readout on the CEM. If it is found that they do not work they will simply be disconnected and the anode line to the ADMEM will be reconnected (it is a LEMO connector) directly to the PMT bases. In this way, there is no impact on the system as it the same as before any installation. If there is enough time before the Run IIb shutdown, we will investigate the possibility of returning to the base modification scenario. In the PEM, there are no splitters so this is not a risk. The PEM harnesses are simple rg174 cables and 50 ohm terminators which are identical to those currently in the system except that they have LEMO's on the ends and not soldered directly to the boards (the LEMO connection is the preferred solution from a noise and reliability standpoint).

Q: What if there are no spare TDC's for the system after all?

A: While funding issues will need to be settled, both Argonne and the University of Chicago have indicated an interest in producing new boards. This would probably double the cost, but they could still be produced by the 2005 installation deadline. Since they are not to be installed downstairs their installation is not coupled to the Run IIb shutdown.

Q: What if we can only procure a fraction of the components?

A: From a schedule point of view, since the system is modular we can instrument parts of the system as pieces become available and still have physics impact along the way. From a final system point of view, for example, if we only get half the ASD's or TDC's we would consider not instrumenting the PEM, or only instrument half of the tubes if we could show that the turn-on curves are acceptable.

Q: What are the research and development risks?

There are very small risks associated with the research and development phase of the project. The parts costs are small compared to the overall project and the labor costs are all University people. The schedule is driven by the Run IIb shutdown date, so the probability of our R&D phase extending beyond 2005 is extremely small. The scope and technical aspects of the project shouldn't be affected unless the prototypes don't work, and there is only a small chance of that. If the current splitter solution doesn't work, we have lots of time to fix it, and in the worst case scenario we can investigate the possibility of going back to the base modification scheme, which will cause schedule slippage, but will still fit within the current Run IIb shutdown time. If the ASD->TDC cable does not perform as expected in the final tests, we can upgrade to a higher quality cable for a small cost increase relative to the overall project cost. The ASD's, TDC and PEM harnesses are already in use in the existing HADTDC system to the probability of them not working as expected is very small.

Q: What are the production risks for the various parts?

All pieces of the various components are off the shelf parts, the dominant costs are the ASD's and the TDC's, and the schedule is driven by availability of the detector for installation. All the parts are either purchased or we have quotes from reputable companies and the lead times are small compared to the time until the detector is open. Therefore even a large increase in the percentage cost (which is low probability) would have a small impact on the overall cost. The labor and testing of the components is small both in terms of time (compared to the shutdown time) and overall cost.

The dominant risks are the low probability occurrence that we cannot create all the ASD or TDC boards since they have larger technical design requirements. In this case, there is risk to the cost (it would cost more to make new ones from scratch), and if we couldn't make all of them there is a risk that the scope of the project would have to be reduced.

Q: What are the other risks?

There is a risk that we can't get or easily get the crate parts. While these have low probability, we can potentially generate spares from test stands. A second option is to slightly modify the crates downstairs and install the TDC's in those crates. However, many tests to insure noise problems would have to be studied.