1 Performance of a Magnetised Scintillating Detector for a Neutrino Factory Scoping Study Meeting U.C. Irvine Monday 21 st August 2006 M. Ellis & A. Bross

2 Outline  Detector description  Simulation  Digitisation  Data Set  Reconstruction  Performance: u Reconstruction efficiency u Charge mis-ID rate u Momentum resolution  Next steps

3 Detector Description  All scintillator box (15m x 15m x 100m) sitting inside a magnetic field (e.g. ATLAS style air toroid).  Basic unit is a triangular pyramid: u base 3 cm u height 1.5 cm u length 15 m  Uniform 0.5T magnetic field simulated (see Alan’s talk for discussion of options and cost)  Digitisation takes into account dE/dx in scintillator slab and reasonable light yield, but does not take into account propagation effects (small effect).

4 Real Scintillator (from MINER A)

5 Full Detector 15 m 100 m Total mass: 22.5 kT

6 Simulation  GEANT4 (8.1) simulation – improved MCS model for muons  Each slab is modeled in the G4 description (parameterised solids to build an “X” and “Y” plane. Many modules containing one of each are placed down the z axis).  All relevant physics processes are switched on.  Magnetic field is simulated as a uniform 0.5T field.  Primary particles are generated as either positrons or positive muons.  Momentum between 100 MeV/c and 15 GeV/c simulated for muons and positrons.  Initial position just inside the “entrance” to the detector (i.e. upstream if there were a neutrino beam).  Flat initial position between +10 and -10 cm in X and Y  Initial direction gaussian with a width of 100 mrad in X’ and Y’

7 Digitisation  Detector is broken up into: u 3333 Modules (X and Y plane) u Each plane contains 1000 slabs u Total: 6.7M channels (single-ended readout)  All hits on the same slab are collected into a single Digit.  dE/dx in scintillator is scaled to be equivalent to 20 Photo Electrons for a muon passing through the full height of the pyramid (i.e. 1.5 cm).  Energy resolution of the readout electronics is simulated to be 2.0 Photo Electrons  0.5 Photo Electron cut is applied after merging hits into a single digit.

8 Reconstruction  Clusters and Space Points are built as described at last meeting.  Pattern recognition attempts to find isolated tracks, works well for muons, needs more work to correctly identify the electron track before the shower (being pulled by hits from the shower), so no results from positron data.  Kalman track fit using RecPack, bug in msHelixNoiser that was identified at previous ISS meeting has been fixed.  Wanted to use same quick fit code as Anselmo for comparison of results, but ran out of time.  Space point/momentum resolution and PID plots from previous talk.  Tracking efficiency and charge ID for muons are with new tracking code.

9 Data Set  Momentum between 100 MeV/c and 15 GeV/c  Muons and positrons.  All simulation jobs completeted on time.  Reconstruction took longer and is still running.  For this talk, look at muon data between 100 MeV/c and 10 GeV/c (consistent with range presented at previous meeting).  Statistics higher than previous study, needed to look at charge mis ID rate.  2.3M muon events: u 0.9M between 100 MeV/c and 1 GeV/c u 0.9M between 1 GeV/c and 10 GeV/c u 0.5M above 10 GeV/c  1.8M events reconstructed for this analysis

10 Position Resolution (RAL meeting) Position resolution ~ 4.5 mm

11 Low Momentum Muons

12 High Momentum Muons

13 Muon Momentum Resolution

14 Electron Identification (RAL meeting) Red Red: Positrons (0.3T) Blue Blue: Muons (0.3T)

15 Muons – Reconstruction Efficiency

16 Muons - Charge mis-ID Rate

17 Conclusions  With existing scintillator technology and plausible readout: u Position resolution ~ 4.5 mm u Muon momentum resolution is better than 10% over range 100 MeV/c – 10 GeV/c u Charge mis-identification rate O(10 -5 ) for momentum above 400 MeV/c u Track reconstruction ~ 100% efficient above 400 MeV/c u Particle ID (electron/muon) from dE/dx measured in scintillator seems plausible above 600 MeV/c  Potential engineering issues: u 15m long scintillators u Large number of channels (of order 10M) to readout. u Magnetic field! – See Alan’s talk...