1. Scintillation counter installation on EBC cryostat scintillators gap scintillators location of MBTS scintillators MBTS counters will be plugged into fiber assemblies for 1/8 of cryostat scintillators

2. MBTS trigger The goal of the trigger is to be able to define 1(2) filled bunches in conjunction with activity from the collision point ATLAS Tilecal trigger cables will run from extended barrel up to rack where signals will be distributed through patch panels  understanding is that gap scintillators will be separated out through own connector  Q: what is meant by gap scintillators? Sometimes cryo scintillators are termed gap. Will find out.  MBTS counters will be plugged into PMT#1 (E#) which uses the muon trigger output; this may be bundled with other Tilecal trigger signals and will require intervention to separate out

3. NB We will have to remove a cryostat scintillator for each MBTS counter in order to route the MBTS pigtail to the optical fiber assemblies Can re-install only between runs

4. Higain counts events 50 mV trigger threshold 4.6mV/pC at end of trigger cable X5 gain in coincidence board before descriminator 12.5pC = 1024 counts (higain) => 50mV threshold = 178 counts on higain output 50mV threshold Tests performed at Chicago test-bench with counter good separation between signal and noise offline; 30-40% efficiency per counter for mip at trigger level; trigger electronics not designed for this kind of signal See however next slide

5. Muon trigger outputs One of the PMT channels on each module has been modified to have a higher gain (X30) for the L1 trigger output The pigtails are long enough that inner and outer segments can be plugged into the modified channels on two adjacent Tilecal modules This will boost signal and will boost S/N by an unknown amount (how much of noise is upstream of additional gain?)  tests suggest 75% efficiency with 90% noise rejection Noise problems currently with finger supplies; would like to check once situation is stable again with new trigger cables

6. Trigger signals What to do with trigger signals once they leave patch panel? Is there a reason not to use the Chicago stand-alone boards?  I think Nick had an objection but I can’t remember what it was Otherwise, we discussed using a VME crate (either separate or sharing space with another system) and commercial logic boards that allow different combinations to be formed  A and C, A or C, etc  If need be I can look for money for buying components Output signal then goes to CTP

7. Issues From Nick’s email to Ana  can test trigger outputs of EBC drawers in ~1 month  will get an idea of signal to noise using muon trigger outputs Sometime later (how much later?) can use temporary trigger cables to send signals up to USA15 Better to wait until final EBC extended barrel trigger cables are installed? How to test counters in place? Can we bring a source down to the cavern? How to measure radiation damage/aging? Keep track of average pulse heights from counters?