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

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  X 10 6 ch – $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