---------------------------------------------------------------------- EG met with Dean Schamburger regarding electronics for the SOLENOID TEST in September 1997 and/or RUN II ~ 1999 posted 9-MAY-1997 19:53:25.29 ---------------------------------------------------------------------- Discussion below is relevant to the the solenoid test unless otherwise indicated. ---------------------------------------------------------------------- GENERAL READOUT: The Run II BLS, ADC, unix system, D0 clock and triggers will not be available for the solenoid test. However, the Run I system still exists and is in principle operational though some of the online nodes have steadily disappeared. We can probably take data through the existing BLS -> ADC -> host (VMS) Run I trigger framework even if we use run II preamps (but see notes below). We can probably use the old timing system(?) We want to read out calorimeter only and need look only at ICD channels. TRIGGERING: Fortunately, we are not planning to trigger on cosmic rays or radioactive sources. We will trigger on some LASER or LED calibration system and possibly have a pulser. Signals from these systems can be directly input into the trigger framework. Need to talk to Dan Edmunds. Trigger framework sampling frequency is 3.5 microseconds. PULSER? A modified pulser is necessary for the Run II preamps because of the faster shaping time. However since the person assigned to designing it has left the field, and no-one has taken over that work, it will be a while before one sees anything. Dean has in the budget enough money to make two spares (one each North and south), which he assumes we would use, at least for checking the electronics. It will probably have the same 32 lines, one for each "pattern", but that has not been finalized. PREAMPS: Dean has been talking to Lynn Bagby et al about our preamp requirements. The capacitance of various calorimeter channels varies from 0 to 5 nanoFarads, thus the different flavors (4?) of preamps which are now on the table. The ICD detector capacitance is very low (<<1), so we want the 0 capacitance version. The Run II preamp will put out 3 x the Run I preamp gain. The Run II BLS expects a 3 x more signal (input) but Run II BLS output to the ADC is the same as in Run I. I think we are shooting for the same light amplitude to the PMT in Run II as we saw in Run I. We want the same sensitivity to charge at the preamp. Since the Run I BLS is expecting 1/3 x the signal (amplitude) of the Run II preamps, we have 2 options: 1. use 66 pF feedback capacitor in (solenoid test) preamps or 2. use 22 pF feedback capacitor and attenuate the signal between the preamp and the Run II BLS by a factor of 3. Dean suspects the preamps cannot handle option 1, but he thinks the preamps can work and be stable with option 2 specs. Therefore, we should pursue option 2 again using a 22 pF feedback capacitor as in Run I, with an attenuation in the preamp to BLS pathway for the solenoid test. For Run II, no attenuation is necessary. PREAMP POWER SUPPLIES: No Run II preamp power supplies will be ready by the solenoid test. Even if they were ready, these units are designed to run 4000 (!) channels at a time, so he thinks 12 (preamp) channels run off one of these supplies will probably go up in a poof of smoke. Dean suggests using bench supplies (standard lambda unit has 3 channels in one chassis). Lambda channels are current limited (with a dial), which should prevent any fried electronics for the solenoid test. We also discussed the Run II LV supply problem: running a single cable to each ICD crate presents a safety problem. Need to talk to Rick Hance about Fermilab safety specs for running this voltage/current over this distance. This is why those little resistors were on the ICD "fanout cards", and perhaps could be why the LV was fanned out on the platform rather than where the HV fanned out. SIGNAL PATHWAYS: The only person who can access the ICD/MG "merge cards" is Joan Guida, however, I anticipate we will leave these merge cards alone for the solenoid test at least. The T&F cable from the ICD/MG merge comes from the ICD fanout card will be rerouted directly to the ICD crate, with perhaps a splice to new cable if this one is not long enough. One question this will answer is "how far will these T&F cables reach?". Ed Podschweit is the man to talk to about the physical despagettiing some of these cables through the platform. For the solenoid test, we probably can splice cables and leave them anywhere, but for Run II, we expect the merge cards will remain in use. We will have to carefully think about how these signals will be physically routed and how much space do we need to hold and protect spliced cable connectors securely. Marvin needs to be consulted RE: platform space, but not till we have more info (on current T&F lengths). SOLENOID TEST DETAILS: are poorly defined. Central iron must close or structural integrity is compromised. South end iron will not be closed, nor will the south EC be on the platform. Field on the south will be greatly distorted with no end yoke for flux return. There is some question about whether the north end iron will be closed, which raises questions about flux return on the north also. With these issues up in the air, we will may not be operating anywhere close to Run II conditions, does it matter?