1. DoE Review June 26, 2000 A Magnetic Tracking Calorimeter for a Neutrino Factory - Ideas & Issues Jeff Nelson William & Mary Williamsburg, Virginia 1 st Meeting, Detector Working Group International Neutrino Factory & Super-beam Scoping Study CERN 22, September 2005

2. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 2 Preamble Some history >Studies of sampling trackers for super beams >Reminder: comments from my nufact05 talk Making a large device >Ideas from MINOS, NOvA & MINERvA >A concept I think we can build as a starting point Thoughts for moving forward Outline

3. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 3 What Should It be Able to Do? Goal: map the oscillations down to the 2 nd dip >Down to 2 GeV neutrinos Want to get … >Good muon charge ID >Good hadronic calorimetry for neutrino energy Harder as E had goes down Can get … >Good electron counting (without charge ID) Is this useful? What resolution is useful? Can we get do tau ID/counting like NOMAD? >How pure is useful?

4. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 4 Starting Out How should we develop a iron tracking detector for the neutrino factory? My thoughts … >Start with things we know well from other detector development projects >Take something we can build, see its performance & optimize Needs iteration with physics working group >If substantial extrapolation from current devices is suggested by optimization, then we’d want to try a real device in a particle beam

5. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 5 Other Good Starting Places NuFact Workshops >S. Wojcicki (Nufact01) Review of many options – analytic calculations No obvious reason why an iron/scintillator tracker not adequate >A. Cervera (Nufact04) Review of large magnetic detectors FNAL Proton Driver Studies >Exploration of off-axis detectors in 2 GeV – 1cm steel & scintillator >e.g. hep-ph/0204208, hep-ex/0206025, hep-ex/0304017 NOvA >Electrons & muons with a 2 GeV neutrino beam >Both sampling version and totally active version >Sampling version (2004 version) & final proposal hep- ex/0503053 >Prior work: P Border, et al, NIM A463 194-204, 2001 MINERvA >High resolution scintillator device for few GeV neutrinos >hep-ex/405002 and CDR (12/04)

6. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 6 A MINOS Scintillator Plane Strips assembled into “modules” 8m diameter 192 strips per plane

7. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 7 FD Steel Plane Make from 2m-wide pieces

8. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 8

9. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 9 Steel Plate Bigger device will be composite like MINOS FD >Widest single sheet of steel in US is 3.9m wide >~15m longest length to cheaply ship (in US) >Suggests a 4 element laminate like the MINOS FD

10. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 10 First MINOS FD beam event A 13GeV stopping muon measured by range & curvature

11. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 11 Defocused rock muon event 4 GeV stopping track (defocused)

12. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 12 Near Detector Event MINOS Preliminary E track approx. 1.5 GeV Low-energy track from fiducial region

13. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 13 Additional Near Detector Events MINOS Preliminary E track approx. 3.1 GeV Medium energy track from near peak in “pseudo-medium” beam

14. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 14 Cost Scaling Want massive device Do not break the budget Can we get an upper limit on the cost?

15. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 15 Making a Magnetic Field Full geometry FEA simulations including all gap structures Plot of |B| (T) Field is an average of slices through a FD plane Average field is roughly 1.3T Modest drop off in corners

16. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 16 B-H Curve for MINOS Steel How strong a field? MINOS used 1006 low-carbon steel >Mass produced for stamping auto panels >We can use reject grade steel at discount Can get somewhat above 1.5T with a reasonable current >That is about the limit

17. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 17 Making a Bigger Torus FEA by R. Wands (Fermilab) & J.K. Nelson >No inherent limitations in current >I = 40kA * (r/10m) >Recall MINOS ND is 40kA Perfectly feasible

18. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 18 Readout Options RPC vs Solid Scintillator >Costs are indiscernible >[NOvA 11/03 proposal appendix & PAC presentation from 11/03 (next slide)] Solid vs Liquid >Active components 33% cheaper for liquid

19. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 19 50kt NOvA Sampling Detector The sampling design had ~400m 2 and 1000 samples Not fully loaded costs – only to show relative scaling Use absolute costs from NOvA Proposal (summary in a later slide) Solid PMTSolid APD Liquid APD Scintillator 22.3 27.3 14.2 optical fibers 12.0 Scintillator Assembly 25.7 21.4 13.5 Photodetector 7.5 1.7 Electronics (not DAQ) 15.3 8.4 Sum 82.8 70.8 49.8 ($M)

20. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 20 MINOS has too much light (& works too hard to get it!) Distance along the scintillator (m) Number of observed photoelectrons APDs vs PMTs Cost dramatically lower per channel 8× quantum efficiency of a M16/M64 PMT APD relaxes the light yield requirements >Allows longer cells >Allows smaller fibers

21. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 21 NOvA Far Detector Liquid scintillator cells >1984 planes of cells Cell walls >Extruded rigid PVC >3 mm outer; 2 mm inner Readout >U-shaped 0.8 mm WLS fiber >Acts like a prefect mirror >APDs (80% QE) 0.8 mm looped fiber 15.7 m

22. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 22 NOvA instrumented area is huge >30kt of instrumentation >1984 planes of 246m 2 -> 55k$/250m 2 For not to much cost can make a much more massive detector by adding Fe >Structure & iron (~M$/kt) Full costs from NOvA TASD (3/05)

23. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 23 MINERvA Optics (Pioneered by DØ Preshower) Significantly enhance position resolution for wider strips Could make the same cell geometry for liquid cells too Particle

24. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 24 A Strawman Concept for a Nufact Iron Tracker Detector 15m diameter polygon >4 piece laminate >Can be thin if planes interconnected e.g. down to 1cm >Idea from 1 st NOVA Proposal 60kA-turn central coil >0.5m x 0.5m >Average field of 1.5T >Extrapolation of MINOS Triangular liquid scintillator cells >Structure based on NOvA using MINERvA-like shapes >4cm x 6cm cells (starting point) >3mm thick PVC walls >Looped WLS fibers & APDs A sample would look like >1 cm Fe >0.7 cm PVC >3.3 cm LS >2/3rds Fe; ρ ≈ 2 >Based on 175M$ for 90kt

25. NuFact ISS CERN 9/05 J. Nelson Iron Tracker 25 Summary Detector is feasible >Large area toroidal fields can by directly extrapolated from MINOS design >Can now make an affordable large are scintillator readout with NOvA APD technology >Enhanced position resolution with MINERvA-like triangles >Costs are all from 2004/2005 Optimize sampling to get lower tracking threshold for charge ID >Would also give good electron counting Come up with parameterization of resolutions, efficiency/fake rate, & costs for optimization