1 / 8

Neutron Background Simulation

Neutron Background Simulation. R. Wilkinson. Neutron Background Simulation. Long-lived neutrons created, diffuse around collision hall They get captured by nuclei, emitting a photon Compton scattering or photoelectric effect makes MeV electrons, which cause hits in muon chambers.

ronny
Download Presentation

Neutron Background Simulation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Neutron Background Simulation R. Wilkinson

  2. Neutron Background Simulation • Long-lived neutrons created, diffuse around collision hall • They get captured by nuclei, emitting a photon • Compton scattering or photoelectric effect makes MeV electrons, which cause hits in muon chambers

  3. Why is neutron background hard to simulate? • Because neutrons can live up to a second before making a signal • They can’t be treated like ordinary minimum-bias pileup, because millions of collisions in the past can contribute

  4. GEANT Simulation • QGSP_BERT_HP physics tables • Other options needed to give long-lived, low energy particles • No pT cuts or eta cuts • Long tracking time • No neutron threshold

  5. Old Methods • Parametrization (UC Davis) • Database of Chamber Hit Patterns (Wilkinson) • Meant to be added only to chambers with signal

  6. CSC-specific issues • Usually only affect one layer, sometimes two, sometimes more. • At L =1034, we expect at most 3% chance of a neutron per chamber, per BX. • We had thought that the trigger would suppress most of these, but it doesn’t! • We had thought suppression used LCTs, which require four layers • So we thought we should only add neutron hits to chambers that already have signal • In reality, it uses CLCT pretriggers, which only require two layers • Which means we need to simulate all chambers, and implement a more accurate zero suppression in the simulation

  7. Workplan • Treat neutrons like regular pileup • Take SimHits with a high time of flight, change the TOF to 0-25 ns, and save the new hits in a different collection. • SimMuon/Neutron/src/NeutronProducer.cc • Keep relative timing for hits within the same chamber • Drop all data except the high-TOF hits from the events • Let the MixingModule mix in the new events. • Use the average number of interactions per bunch crossing, including gaps • Should get the correct occupancy, assuming steady-state running. • Should just work for DT & RPC

  8. CSC Workplan • Current Simulation: • Saves any layer which has signal • Only simulates and reads out groups of strips (CFEBs) containing or near signals • Doesn’t always make all the noise strips needed • What’s needed: • Create a transient container of unsuppressed digis • Neutron hits come from MixingModule • Run the L1 trigger primitive simulation • Move the module from the L1Trigger sequence to the SimMuon sequence • Code would still live in L1Trigger • Input is unsuppressed digis • Creates a new transient collection of pretrigger digis • Make a zero suppression module which produces the suppressed digis • Generating noise, if needed • Prototype in SimMuon/CSCDigitizer/src/CSCDigiSuppressor.cc

More Related