Notes on Trigger Programming for e94104, e98108, and e00102 =========================================================== For other experiments search the README* files on adaq account in the trigger directory. update Oct 4, 2001 experts: R. Michaels and B. Reitz I. Overview The main triggers (T1 on R-arm and T3 on L-arm) and T3 on L-arm) are formed from an overlap of S1 and S2 scintillators. This is described in detail below. The triggers are T1 = Main R-arm trigger T2 = Loose R-arm trigger, for measuring efficiency T3 = Main L-arm trigger T4 = Loose L-arm trigger, for measuring efficiency T5 = coincidence of T1 and T3. In addition, the old S-Ray trigger (involving MLU) will be formed, but not put into trigger supervisor, hence no events of that type. Instead the S-Ray trigger will only be put into a scaler, its rate should be similar to the main trigger. The MLU is used to form T2 and T4. It could possible be used to form additional triggers that require other detectors. Let us first describe the MAIN TRIGGER, T1 and T3, which is based on scintillators. First the Left and Right PMTs are AND'd. There are then 6 signals from each scintillator planes S1 and S2 (the result of L+R). These 6 are OR'd to make one signal each from S1 and S2. Finally, the trigger is the AND of these two signals. Here is an ASCII diagram: S1 - paddle 1 - Left --\ S1 - paddle 1 - Right ---AND --> S1 - paddle 2 - Left --\ \ S1 - paddle 2 - Right ---AND --> \ OR of S1 paddle 3... 6 \ \ \ AND -------> T1 (T3) / / S2 - paddle 1 - Left --\ / OR of S2 S2 - paddle 1 - Right ---AND --> paddle 2... 6 The timing at the trigger supervisor will be such that T5 arrives thus it takes priority in deciding the event type. However, one may look at the trigger latch pattern to see which triggers coexist. A ``trigger latch pattern'' in the datastream shows the pattern of triggers which co-exist in an event. This is a TDC 1877 (multi-hit with up to 6 hits, a 5 microsec window, one trigger on each of 12 channels, each channel a separate trigger) which shows on channels 1-12 the trigger 1-12 AFTER prescaling. So, if a T5 is accompanied by a T3 which survived prescaling, one would see a signal on channels 3 & 5 with the appropriate timing. This trigger latch pattern is called ``spare7'' in the detector map. How the coincidence time is measured, and some explanation of the glitchy features seen there, are explained in this document: ctime.ps (postscript). Electronics deadtime is a complicated issue. There can be losses in the trigger electronics, but also smearing of distributions (TDCs, etc), and pileup in VDCs. To provide a handle on some of these things we have implemented a scheme to measure the electronics deadtime. II. MLU Programming -- Concepts MLU#1 Generate S-Ray pattern mlu1_Sray_left_generate.dat mlu1_Sray_right_generate.dat (left and right spectrometers) R-arm has bit 14 bad, hence different. Generate S1-or and S2-or (same files, though bit 14 bad on R-arm). s1or_generate.dat s2or_generate.dat Since Jan 1, the S-Ray trigger plays no role anymore, but it is put into scalers to count. MLU#2 This MLU is run in strobed mode with the strobe coming from the OR of S1, S2. That means that at least one of S1,S2 planes must fire. Bits 1 = S1-or 2 = S2-or 3 = Gas-Cerenk (if exists), or S0-PMT#1 (if exists) 4 = S0-PMT#2 T2, T4 logic Ignore S-ray Veto if main trigger exists. For e94104 and e98108: Require S1-or or S2-or. Don't require Cerenkov. For e99117 and e97103: Require 2 out of 3 from among S1-or, S2-or, and Cerenkov-or. For e00102: Require 2 out of 3 from among S1-or, S2-or, and S0. S0 requires both of its ends to fire. Generate T2, T4 with mlu2_t2_generate.dat mlu2_t4_generate.dat These generation files have changed slightly since Jan 2001. For convenience I have saved the mlu2* files that were generated and used: mlu2_t2_e94104.data, mlu2_t4_e94104.data used by e94104 and e98108 mlu2_cer_t2t4.data used by e99117 and e97103 mlu2_s0_t2t4.data used by e00102 III. Technical Details of MLU Programming The following is a typical script for generating the MLU files. #!/bin/sh # Directory is adaql1:~atrig/trigger/mlu # Make Sray for left spectrometer XYmlu -f mlu1_Sray_left_generate.dat mlu_compress mlu.data rm mlu.data mv mlu_compress.out mlu1_Sray_left.data # Make s1or and s2or (used for both spectr.) XYmlu -f s1or_generate.dat mlu_compress mlu.data rm mlu.data mv mlu_compress.out s1or.data XYmlu -f s2or_generate.dat mlu_compress mlu.data rm mlu.data mv mlu_compress.out s2or.data # merge to form mlu1_left mlu_bitmerge mlu1_Sray_left.data s1or.data mv mlu_bitmerge.out temp.data mlu_bitmerge temp.data s2or.data mv mlu_bitmerge.out mlu1_left.data # Make Sray for right spectrometer XYmlu -f mlu1_Sray_right_generate.dat mlu_compress mlu.data rm mlu.data mv mlu_compress.out mlu1_Sray_right.data # merge to form mlu2_right mlu_bitmerge mlu1_Sray_right.data s1or.data mv mlu_bitmerge.out temp.data mlu_bitmerge temp.data s2or.data mv mlu_bitmerge.out mlu1_right.data rm temp.data # make MLU2 file for t2 XYmlu -f mlu2_t2_generate.dat mlu_compress mlu.data rm mlu.data mv mlu_compress.out mlu2_t2.data # make MLU2 file for t4 XYmlu -f mlu2_t4_generate.dat mlu_compress mlu.data rm mlu.data mv mlu_compress.out mlu2_t4.data ======================================================= Appendix -- MLU utilities routines Type the name of the utility without arguments and it will introduce itself, and explain its usage. XYmlu -- takes a pattern like 10xx01 and generates all mlu entries. 1=bit must be true; 0=bit must be false; x=bit may be 0 or 1. There is a Y option, but it is little used and not too important. btst -- Examines a pattern of bits mlu_compress -- Takes an mlu file and examines all pairs of line-entries. If the two line entries are identical, one is kept, the other discarded (this isn't really necessary but speeds up the download). Also the bit-wise OR of 2nd components is taken if first components are identical. mlu_compare -- Compares two mlu files to see what is different. If no optional argument is given, any difference in the file are noted. If an argument is given (any number), only the first entry of each pair are compared. mlu_bitmerge -- Merges two mlu files. For each pair of line entries "X1 Y1" from file 1 and "X2 Y2" from file2, if X1=X2, then the two entries are merged to form bit-wise OR of Y1,Y2, i.e. we get "X3 Y3" where Y3 = Y1 | Y2.This page maintained by rom@jlab.org