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Enhancing MuCal Design for Improved Particle Detection

Learn why an improved MuCal design is imperative to address funding uncertainties, complexity in muon detection, and energy measurement challenges. Explore the principles of improvement, quick simulation, rapid analysis, benefits, and drawbacks.

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Enhancing MuCal Design for Improved Particle Detection

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  1. Improving MuCal Design • Why we need an improved design • Improvement Principle • Quick Simulation, Analysis & Results • Pros & Cons Jean-Sébastien Graulich

  2. Why an improved design • CKOV2 funding is uncertain • EmCal mu+/e+ is not straightforward • Using many parameters with Complicate (Neural Net) Analysis • Stability vs MICE configuration ? Systematics ? • Separation Requires • P and TOF measurement -> How do we do in Stage I ? (No P measurement !) • Precise Energy Measurement -> ADC Problem • EmCal (Kloe) design is optimized for higher energy muons • 200 MeV/c muons are stopped in the middle • Inhomogeneous material-> spread in muon range -> spread in visible energy Jean-Sébastien Graulich

  3. Improvement Principle • Start with a rather thin high Z material layer • Stop primary positrons and convert them into gammas and soft e+/e- • Several layers of plastic scintillators (low Z) • Large Muon range -> long tracks with large energy deposit/layer • Soft e+/e- -> scattered hits with small energy deposit • Nearly Transparent to gammas (low Z) • Problem with low energy muons (<120 MeV/c) • They stop in the first (high Z) layer • Maybe TOF can help e+ µ+ Jean-Sébastien Graulich

  4. Quick Simulation • First layer (Converter) = 1 Kloe layer (4 cm thick, 8 cm wide) • 11 Layers of scintillator, 2 cm thick, 8 cm wide (15 slabs/layer) • A passive plastic layer has been introduced : bad idea ! • This kills the muon detection efficiency below 150 MeV/c • Mu Efficiency is estimated only above this threshold • Many thanks to Rikard 162 MeV/c Muon Passive 6 cm Kloe4 cm Jean-Sébastien Graulich

  5. Simulated Beam • Using an old Turtle beam (small divergence) • Same as Rikard used 3 month ago • Small number of positrons • 256 e+, only 199 reach MuCal in a 20 ns time window. 35085 µ+ over 150 MeV/c Jean-Sébastien Graulich

  6. High thr: 2.5 MeV Low thr: 200 keV Quick Analysis • No realistic digitization yet • Using True Visible Energy with 10% resolution • No charge measurement: • Only two level discriminator: low/high signal • No clustering, signal sharing ignored. • Muons • Positrons Jean-Sébastien Graulich

  7. Quick Analysis • Looking at Track Length • Counting only high level hits • Taking the maximum length of continuous track • X,Y Segmentation not used, the highest hit in the layer is taken • Looking at low level hits • Just count the layerswhere there is a low level hit and no high level hit • Again X,Y Segmentationnot used • Rem: • X,Y Segmentation is used only fordigitization, not for analysis e+ have short tracks andmany low level hits Muons have long tracks and no low level hits Jean-Sébastien Graulich

  8. Quick results • This can be reduced to one single parameter • Continuous intense track length index = High level track length divided by the number of sparse low level hits Cut at 1 Jean-Sébastien Graulich

  9. Results Summary • Muon efficiency (over 150 MeV/c): 99.7 % • Positron rejection efficiency (all energies): 98.4 % • Purity of the muon sample: 99.98 % • Main Losses: mu decay either in flight or in the time window (20 ns) Jean-Sébastien Graulich

  10. Background study • Main background: • Coincidence with muon decay • Either the one just arriving or a previous one • Main effect: • The continuity of the track is affected; a muon is misidentified as a positron • Small bias (decay in flight probability slightly depends on the momentum) • Higher order effect: • The decay product piles up with a positron, producing a fake track. • Highly suppressed by geometric factor if segmentation is used in the calculation of the track length • Case studied: • A muon piles up with its own decay product • Studied by increasing the time window at the digitization level: 20 ns -> 100 ns • Results: • Mu Efficiency drops to 97 % Jean-Sébastien Graulich

  11. Easy mu/e separation 1 parameter with physics signification No need for CKOV2 Simple, “cheap” technology No need for good energy resolution Similar design can do mu/pi separation in Stage I (ask Rikard) Allow triggering on high P muons (in phase w RF) Need more Pmts Who can build it? Need help to find more cons… Pros and Cons Jean-Sébastien Graulich

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