Simulation of a Magnetised Scintillating Detector for the Neutrino Factory

1. Malcolm Ellis & Alan Bross Fermilab International Scoping Study Meeting KEK, 23 January 2006 Simulation of a Magnetised Scintillating Detector for the Neutrino Factory

2. Long-term Goal • Support existing simulation and analysis efforts (Cervera et. al.) by providing momentum resolution, charge mis-identification, etc from a full simulation and reconstruction of potential detectors. • Allow for “credible” technological extrapolations • No cost or WBS consideration at the moment • Results can be parameterised and then used for fast simulations. • Aim to study optimum detector layout as a function of a few design parameters including module size, shape and magnetic field.

3. Basic Detector Concept 7.5 mm 15.0 mm Considered Extremely Fined Grained

4. Magnetic Field • Has not been investigated in any detail yet. • Considering two options: • Iron sheets in between scintillator layers. • Parameters to study are thickness of each sheet and ratio of scintillator to iron. • More work needed to understand how to accurately simulate the field and perform reasonable reconstruction. • Air toroid magnet surrounding detector. • ATLAS magnet is a starting point in terms of scale. • Simulating 0.15 T field to start. • Will study physics parameters (P resolution, charge ID, etc) as a function of magnetic field

5. Procedure • Simple GEANT4 application built to create scintillator structure and track single particles through (muon or electron at the moment). • Normal physics processes are on. • Simple digitisation at the moment. Will need to decide what readout technologies to study in order to chose more appropriate values. • Reconstruction program using the RecPack package performs a Kalman fit of the reconstructed points from the crossing X/Y hits.

6. Status • Past month spent in code development and testing. • Simulation now at a stage where they can be used for production of a high statistics sample for serious analysis. • Reconstruction still requires some work to fine tune track fit. • Need to define a list in order of priority of conditions to study and what results are required. • First list looks like: • Momentum resolution • Charge identification • Particle ID (dE/dx) • Two track separation • Jet angle and total energy resolution • Hadronic response • Neutron detection

7. Muon 3 GeV/c

8. Electron

9. A First Look • Study muons in the range 100 MeV/c to 3 GeV/c (7.5k events) and 3 GeV/c to 50 GeV/c (2.5k events). • First pass looking at general track fit quality and momentum resolution in particular. • Pattern recognition is “perfect” (or cheating!) as I use Monte Carlo truth to select the hits that belonged to the primary track (100% purity and efficiency). • Once hits are selected, clustering, space point and track reconstruction proceed without the use of Monte Carlo truth information.

10. Point Reconstruction • Digitisation assumes a most probable light yield of 20 PE for a muon traversing the full height of the triangle (7.5 mm). • Space point position determined as the PE weighted average of all slabs where the signal was above 1 PE. • Resolution improved from ~3.8 mm to ~1.3 mm.

11. Point Resolution

12. Number of Slabs in a Space Point

13. Track Reconstruction • Kalman filter provided by the RecPack package. • Track fit includes multiple scattering and a simple dE/dx model. • dE/dx model still needs some work.

14. Track Fit Quality

15. Momentum Resolution

16. Next Steps • Improve dE/dx model to remove pulls from track fit. • Study using range for muon momentum determination • Repeat study with electrons and look at use of dE/dx measurement along a track for particle ID. • Define list of design parameters and physics parameters to be studied. • Start productions for first proper result. • Consider looking at more complicated topologies and study the hadronic jet of neutrino interactions.

17. Is this Detector Scenario Credible? • Technology is not really an Issue • COST IS • Assume a 25kT all scintillator detector with air-core magnet (B = 1-3 kG) • Of course the study will also include magnetized Fe • Much larger Fiducial mass • Or could add non-active target in air-core design • Scintillator (Solid or Liquid) – No R&D issues • Cost (solid) - $100M • Segmentation as shown here gives » 7 X 106ch • $10/ch is possible - $70M • Fiber Cost – Assume high QE PD and high yield scint. Use 0.4mm fiber • $0.16/m » $16M (Very important optimization – 1 mm fiber is 6X the cost!) • $100M for magnets + infrastructure, etc • Total is something less than $300M • Not an order of magnitude more than what is acceptable

18. Moving Forward • It is clear that Magnetized Fe detectors are straightforward to build, robust and have low operating costs, - However: • Detailed and rigorous MC simulations will tell us whether or not this technology is worth pursuing for future experiments • Interest will be performance driven • Do the MC model detectors have a physics reach that is noteworthy? • If the answer to the above question is yes • The R&D path is relatively straightforward

19. R&D Areas • Photo-detectors • Already good work progressing on SiPM, MRS, even VLPCs. • Need High QE and reasonable gain • Potential readout chips already exist (integration) • Scintillator • Technology in place for the most part • Co-extrusion of WLS fiber with scintillator • Adjust plastic density (Z) by adding heavy element • Optimization of Scint+WLS fiber + PD • Cost/(pe detected) • Magnets • Natural extrapolation from Atlas? • Assembly and integration • Mild extrapolation from existing detectors • But some significant cost savings with new engineering approaches in a number of areas