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TRIGGER

TRIGGER. a + b ⟶ c + d . Coincidence B ⦁ F , (B,F logic signals). B beam signal, i.e. a selection of particle types a, direction of the beam etc. F final state signal i.e. a selection of the final state topology, particle types etc. . coincidence. Inclusive or.

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TRIGGER

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  1. TRIGGER a + b ⟶ c + d Coincidence B ⦁ F , (B,F logic signals) B beam signal, i.e. a selection of particle types a, direction of the beam etc. F final state signal i.e. a selection of the final state topology, particle types etc. coincidence Inclusive or

  2. Exclusive OR A B C 1 0 1 0 1 0 1 0 0 0 0 ⦁ Anticoincidence input coincidence input output

  3. Rutheford scattering α + Au ⟶ α + Au ⦁

  4. beam + target ⟶ a + b coincidence defines the beam profile anti (C) eliminates beam particles which do not interact ⦁ S,A,B,C scintillators Trigger signal: ⦁ A ⦁ B ⦁

  5. Analog signal Digital signal ⦁ ⦁ ⦁ ADC Charge measurement Multichannel analyzer

  6. Measuring of muon lifetime μ⟶ e + Muon stopped in lead absorber , then decays , electron is detected in B or C Lifetime is the time difference between muon signal and electron signal Muon : A ⦁B⦁ Electron: or

  7. ⦁ TDC ⦁ or TDC time-to-digital convertor

  8. More realistic arrangement Muon is slowed down in the Pb absorbers Muon trajectory is selected by the counters Electron is detected in the counter Counter eliminates background muon: Electron:

  9. BUSY (≡ INHIBIT) signal Digitization by an ADC, writing of this or other information need some time ⟹ it is necessary to block the system from any other event inhibit and busy method flip-flop ( ) If it is present, the gate is open and coincidence is working Output from the coincidence To flip flop ⟹ BUSY signal coincidence is closed To trigger Informations are read out ⟹ clear signal to the flip/flop ⟹ the coincidence is open, other event can be detected

  10. Life time : the system is sensitive to the arriving events is present, which opens the gate , BUSY closes the gate the scaler counts, if the clear signal was send

  11. Trigger F⦁ B , B - beam signal, F- final state signal 1) Beam signal, example target Scintillator counters, , with the suitable gas filling eliminates oter beam particles, p, π A anticoincidence veto , eliminates “halo” particles BC bem counters, used as a veto of events which detect a beam particle a proportional chamber which makes possible to detect one particle in the beam, i.e. one wire is hit only a proportional chamber which detects final state particles

  12. 2) Final state signal F, it is a combination of signal from various detectors which reflects event topologies Multiplicity of particles Directions of particle emissions Particle energies Type of particles etc. Example: the target is hydrogen, decay in the final state 2 charged particles Event topology: at some distance from the target ⟹ 2 tracks Final state: 0 particles just behind the target after some distance 2 particle Trigger: Neutron: no signal ⟹ around target no particle detected

  13. Background: A layer of lead around the target Detector noise or

  14. The trigger system must be complted by detectors for energy and momenta measurement (magnets, chambers, calorimeters etc..) and data acqusition system (DAQ)

  15. Dead time non-extenable dead time, τ dead time when one event is pocessed τ detector is not sensitive to other events during τ The true number of counts k/T ≡ R is the experimental counting rate

  16. 2. Extendable case events extends dead time Distribution of time intervals t between events? ( for the detection t n number of detected events, The mean number of detected events in time period t is mt, m is the true rate

  17. What is the distribution of time intervals t ? The normalized distribution is Distribution of number of events ≡ probabilty

  18. Number of detected events ( or counts) in time T True number of events in time T To find the true value of rate m ⟹ a numerical solution

  19. Measurement of the dead time k/T ≡ R the method of 2 sources the rate of both sources The rate of each source

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