The trigger for the New Electromagnetic Calorimeter NewCal Feasibility studies Charles F. Perdrisat February 17,2012

Assumptions: HERA-B midsection shashlik detectors available, 2128 channels in clusters of 2x2, with 4 FEU-84-3 PMs in each cluster. 2) The cross section size of one midsection detector is 5.59x5.59 cm 2. 3) The proposal NewCal front was ~110x312 cm 2 ; which can be achieved with 20x56 =1280 blocks, neglecting the unknown gap between elements. Largest we can do is 24x72=1728 blocks, 134x402 cm 2. Electronics? 4) First configuration compatible with existing adding circuits. Second and preferred solution: requires use of analog FI/FO’s for second levels. 5) The location of the ”largest” cluster will be correlated with the hadron calorimeter hit position; this part not addressed here: trigger only.

Solid angle matching for 65 msr proton-detector

Conceptual design: The trigger is formed in 3 steps, as in BigCal: first adding signals in the vertical direction (first level), with 2 blocs overlap between each vertical section of 8 (not done in BigCal). Second, adding first level outputs in the horizontal direction (second level), with 2 blocs overlap between each section of 4 (vertical in BigCal). Third, discriminating second level outputs, and reducing logic outputs to 11 channels (or more if required for ep correlation) with FI/FOs, to discriminators, each with different trigger levels, “ored” to reduce to one trigger signals (third level). First level requires 288 input octets, or 144 adders units. Second level input analog FI-FO. The third level requires 33 analog 4-fold FI-FOs, 11 DISCRIs set at a different trigger level (more on that later), and 3 4-fold logic FI-FOs, to form one trigger.

Twenty four columns. Showing only the first 26 rows for readability

Second level adders. Whether compatible with ep trigger correlation is unclear to me right now. Requires 11x12=132 4-fold analog FI/FOs. The segment of circle approximates constant Q 2 : 12 GeV 2.

Showing how many times the output of a given detector block is required to obtain the overlap patterns discussed so far. Yellow for 1 Grey for 2 Pink for 4

Problems that need to be addressed next 1)Present scheme requires two parallel PM outputs from 432 of the 1728 PMs. 1)It also requires 4 outputs from the first level adder octets; these currently have 3 outputs. We have 112 first level adder modules, and 21 second level modules, total 266 octets plus spares? compare to the need of 264 first level adder modules. 3) About HERA-B middle section shashliks: need to know first: do we get it, YES or NO. Then manpower, cost of transport, no PMs? polarity of HV and more…. I need to establish contact with locals at DESY asap.

Design considerations : Assuming again HERA-B mid-section shashliks, the lead weight of 1 element consisting of four 5.59x5.59 cm bars, is ~18 kg, 40 lbs elements in the calorimeter is 8,200 kg, 18,000 lbs. OK with crane, but must add overall container(s). Design challenge (?). Propose building 3 identical units, each 24x24 bars. Details ito follow.

Combined top view (upper part), and side view looking down the beam pipe (Lower part). NewCal assumed to be monolithic vertical 4 m. Circles are constant Q 2, illustrating the missmatch of this geometry. However, note that acceptance for 9.3 GeV 2 is minimal, but acceptance for 14 GeV 2 is maximum.

Illustrating how to “wrap” the 3 modules around circle of constant Q2. This is rotation in the plane of a circle perpendicular to the beam. Doable, but difficult. Does solve partially problem of energy spread and trigger level accuracy.

Here vertical view in lower part is in plane containing the middle trajectory. To reduce problem of shower spread over many blocks, divide NewCal into 3 identical sections, and orient them around circle centered at target center, and thru detector center. Center of each section at -16, 0 and +16 degrees. Doable. To do both rotations is in my view probably not doable.

Your comments (and advice) are welcomed.

use solid angle 65 msr of p in SBS Ebeam q2 pmom Escat th(e) t(p) th(p) pt pl dp3_dp