Outline: Brief review Splitting of input signals Status of 2A system before and after splitting Status of 2B system after splitting Status of monitoring The future of split signals Christopher Neu L2 Upgrade Second Installation Readiness Review 9 February 2005 Status of Optical Splitting for ShowerMax Input Path

February 9, 2005 L2 Upgrade ReviewChristopher Neu Penn/CDFPage 2 XCES Input Path: Description of Run 2A System Shower Maximum (CES) data used in L2 to reduce trigger rates for electron and photon triggers reduces detector background from single-phototube discharge track-matching to shower max reduces combinatoric background for electrons CES detector: within CEM calorimetry 32 wires at |z| 200cm for each wedge CES charged pulse -> digitized -> 4 neighboring wires are summed in some time slice(4 CDF clocks): 16 wire groups per wedge Compare sum to low and high thresholds: T low = 1.5 GeV, T high = 3 GeV (changed in ~May) Low and high trigger bits are set if wire group sum exceeds threshold 16 wire groups x 2 thresholds = 32 data bits per wedge/evt (called XCES bits) Data flow: SMXR board performs sum and threshold comparison; one SMXR per wedge Single fiber transmits 32 data + 8 for buffer # = 40 total bits from each wedge/evt 48 total cal wedges => 48 XCES fibers into L2 4 RECES boards accept these 48 fibers; use Taxi technology; latch according to L2 buffer RECES boards are aux cards in L2 decision crate (b0l2de00) Alpha reads out XCES bits when needed (for L2 decision making and/or when making TL2D)

February 9, 2005 L2 Upgrade ReviewChristopher Neu Penn/CDFPage 3 Splitting XCES Input Channels Optical splitting problem: –Existing XCES channels driven by TAXI protocol through Agilent optical drivers Significant spread of optical power across system –Optical splitting easy solution is passive splitter Simple prism But incurs 1-to-2 -3dBm optical strength hit (50% reduction in signal power) –Many (about half) of the 48 input channels are too weak to split passively Need for an optical splitter that drives its outputs without significant loss Looked for commercial product – but found nothing that matched our needs (somewhat meager compared to bandwidth of typical current applications) West 1 West 2 East 1 East 2 ch dBm } → Penn designed and built a simple active optical splitter to accommodate all the XCES channels. Details can be found in litter.jpg and CDF 7152

February 9, 2005 L2 Upgrade ReviewChristopher Neu Penn/CDFPage 4 Active Splitter: Implementation The active splitter boards reside in a custom- built crate in rack 2RR31C 15 slots Power provided by two 5V, 20A Lambda supplies Fully driven (15 boards) current draw and power: –-5V: 10.5A –+5V: 600mA –55.5W total dissipated Each supply is fused independently Power supplies are monitored with standard CDF PSM tool Dervin was a tremendous help getting the multitude of fibers routed into and out of the tight space (48 in + 96 out = 144 in 19”x6” space)

February 9, 2005 L2 Upgrade ReviewChristopher Neu Penn/CDFPage 5 Status of 2A Channels Before Splitting 2A system monitored with TrigMon This is run from March. Three figures of merit: Benchmarks: This run is somewhat not representative; other runs had channels with P_miss~0.01.

February 9, 2005 L2 Upgrade ReviewChristopher Neu Penn/CDFPage 6 Status of 2A Channels Before Splitting Recall data collected on the 4- wire groups of the CES is compared against two thresholds (low and high) in forming the XCES trigger bits Red curve is data passing low XCES threshold, blue is high XCES threshold Missing bits can be seen as deviations from 100% efficiency in bottom plots Typical for runs in that era...

February 9, 2005 L2 Upgrade ReviewChristopher Neu Penn/CDFPage 7 Current Splitter Configuration Several active splitters had problems splitting signals from certain XCES channels Mostly problems were identified as higher- than acceptable error rates in the 2A system. Cause is under investigation For commissioning we employ a few passive splitters…twelve of the 48 channels are passively split I do not like this configuration either But it is getting the job done – the goal was to be able to split the 48 channels – and we have that now Once commissioning is over and splitting is a luxury item is we can study how to recover these 12 channels…

February 9, 2005 L2 Upgrade ReviewChristopher Neu Penn/CDFPage 8 Status of 2A Channels After Splitting Results for 2A system: Run – from last week All 48 channels split and within error benchmarks from April. There is one remaining outlier channel: E17, which corresponds to b0ccal13 slot5, which has been a chronic problem for some time. Tough to split and send to RECES card.

February 9, 2005 L2 Upgrade ReviewChristopher Neu Penn/CDFPage 9 Status of 2A Channels After Splitting XCES efficiency versus ADC count – Similar performance as from April. This behavior is monitored for current runs by CO and offline by hand. The performance shown here is typical for the 2A system. Splitting for 2A system has been in place and behaving since the last week of December.

February 9, 2005 L2 Upgrade ReviewChristopher Neu Penn/CDFPage 10 Status of 2B Channels After Splitting 2B system: Low error rate on a handful of channels: E_W ~ 10^-5 Others much smaller. Still measuring what this error rate really is…note 2A system had error rates up to of order 10^-3. E17 and its SMXR are a problem for 2B electronics too… Note P_miss is zero for all 2B channels. The XCES channels are much more robust with 2B electronics.

February 9, 2005 L2 Upgrade ReviewChristopher Neu Penn/CDFPage 11 Review From 9/27 Review Major open issues, manpower and timeline: Present – Oct 15: - understand data integrity issues from beam runs - order jumper fibers - order jumper fibers Oct 15 – Nov 15: - complete AS modifications - test each card for VLTN and in system with L2 torture - test each card for VLTN and in system with L2 torture - system build-up - system build-up - finishing touches on XCES portion of PulsarMon and start running XCES monitoring online - finishing touches on XCES portion of PulsarMon and start running XCES monitoring online Nov. 15: - personal deadline for fully split 48 ShowerMax channels Nov. 15: - personal deadline for fully split 48 ShowerMax channels - monitoring complete and capable of running online - monitoring complete and capable of running online - consistent L2 testing - consistent L2 testing Nov. 22: - beam in the machine Nov. 22: - beam in the machine Dec. 1: - collisions Dec. 1: - collisions All these goals were met at the appropriate times. We had 48 split channels for the return of collisions in early December. Both the splitting and the monitoring evolved over the weeks since the end of shutdown as new problems were identified.

February 9, 2005 L2 Upgrade ReviewChristopher Neu Penn/CDFPage 12 Spare Situation and General Hardware Maintenance Needs AS Boards – 14 are in system; we have 2 spare cards Fuses – we have through-hole fuses and I know where to get more – will have an essentially infinite supply PS’s – have several (~6) spares in case these fail or new ones are needed Crate power supplies – have one Lambda spare, need to purchase a second Crate fuses – These are available Spare jumper fibers – we have ~10 spare Spare input fibers – we have ~10 spare What we need:

February 9, 2005 L2 Upgrade ReviewChristopher Neu Penn/CDFPage 13 Summary and Future of Split Signals Splitting input signals was designed to enable us to commission the 2B system while the 2A system was taking data. We have shown that after splitting the 2A performance is no worse than before the splitters were inserted. We have also shown that the 2B electronics have a much lower error rate in apples-to-apples comparisons. Having a completely split system, while tedious to establish, has been a benefit for the upgrade: - allows completely parasitic testing and comparison to alpha+TL2D - allowed for easier diagnosis of board-dependent problems - allowed to test under realistic conditions - test-stand-like conditions – or anything which is not an exact replica of the real system – is not good enough The split signals minimally need to remain as long as we consider the alpha system to be a hot spare. After this mixed-operating-mode is over, one could continue to utilize the split signals to feed the default 2B trigger electronics and a “hot-spare” version of the trigger system.