1. Segmented magnetised detectors Anselmo Cervera Villanueva Universidad de Valencia ISS meeting RAL (UK) 25/04/06 RAL (UK) 25/04/06

2. 2Overview General aspects Signal and backgrounds Detector concepts Conclusions

3. 3 General aspects In the DIS regime water cherenkov is not suitable One needs a detector capable to measure the hadronic energy In a neutrino factory the measurement of the muon charge is mandatory Segmented magnetised detectors are one of the proposed solutions

4. 4 Backgrounds The golden signal: wrong sign muons The backgrounds are: Muon misidentification (mainly pions) Wrong sign muons from , k decays Wrong sign muons from D decays Hadronic angular resolution helps There is a irreducible component Charge misidentification of right sign muons The ratio (multiple scatt.) /(distance between active planes) is crucial All of them increase when going to low muon momentum

5. 5 Detector requirements Large mass: 40-100 KTons Magnetic field: ~1 T Transverse resolution: ~1cm: Important for D decay rejection Longitudinal segmentation: Important for the charge Large radiation length Important for the charge

6. 6 Active part Scientillators: Type Solid (MINERVA, MINOS, LMD) Liquid (NOvA) Redout PMTs (MINOS) APDs (Minerva, NOVA) RPCs (Monolith, INO)

7. 7 LMD iron (4 cm) scintillators (1cm) beam 20 m 10 m B=1 T 1cm transverse resolution Studies have been done for very small  . Aim for very small background levels (10 -5 ) Strong cut on muon momentum (>5 GeV) Problems to measure the charge of muons below 3 GeV Interesting for intermediate distances (3000 km) to measure very small   Essentialy free of backgrounds But not for second oscillation maximum ( 2-3 GeV) For large   the performance should be good. We must check it !!! By lowering the muon cut.

8. 8 The INO concept ISS-CERN 22-24 September, 2005 Naba K Mondal Tata Institute of Fundamental Research Mumbai, India Similar to LMD but suitable for larger distances because the charge measurement is less efficient (longer distance between measurement planes) Interesting for large distances (~7000km, CERN/RAL-INDIA) Good for the mass hierarchy Is there a design optimised for Nufact (vertical planes) ?

9. 9 The TASD (  A)  Concept Suitable detector for: High gamma beta beam (non magnetised) Neutrino factory: baselines < 3000 Km because it has good detection efficiency down to low neutrino energies (1-2 GeV). Could detect first and second oscillation maxima at intermediate distances:1000-3000 Km See talk by M. Ellis

10. 10 MINERvA Optics (Pioneered by DØ Preshower) Significantly enhance position resolution for wider strips Could make the same cell geometry for liquid cells too Particle Jeff Nelson William & Mary Williamsburg, Virginia ISS - CERN 22, September 2005

11. 11 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 6 cm 4 cm

12. 12 Charge with magnetised NovA Each tube: 15.7m long, 3.8cm transverse to the beam, 6cm along the beam. Precision per coordinate 3.8 / (12) 1/2 = 1.2 cm. Track length given by muon range, but taken to be maximum of 50m. 0.4 Tesla magnetic field Momentum (GeV/c) Range (m) Curvature (1/R) (m -1 ) # Stand. devBkg 2 10.4 0.06 5.6~10 -6 6 29.7 0.02 10.0<10 -7 10 48.2 0.012 13.0<10 -7 20 92.6 0.006 13.0<10 -7 30 135.7 0.004 13.0<10 -7 50 219.2 0.0024 13.0<10 -7 Leslie Camillieri ISS-CERN Set 05

13. 13 Probably the optimum detector is in between NOvA and LMD: liquid scintillator with some iron to facilitate the magnetisation and increase the mass. Detector regions optimised for the measurement of the muon charge is another possibility

14. 14 Very interesting idea This detector would fulfill the requirements 1 cm transverse resolution (normal to the scintillator) What is the resolution along the scintillator ? Very good angular and energy resolution for hadron shower In principle, no problem with muon charge Problem: It is a very long detector !! Would it be posible to reduce the length by including more iron (less hadronic angular resolution) and iron free regions to enhance the sensitivity to the muon charge? It depends on the physics requirements

15. 15 Iron free regions ? A muon of 1 GeV will traverse at least 1 iron-free module One has to design the detector such that the muon traverses at least one iron- free module after the extinction of the hadronic shower, to facilitate pattern recognition. The measurement of the momentum and the charge is considerably improved in the iron-free region. One can probably reduce the number of active planes in the iron region: Less hadronic energy/angle resolution. Find a compromise. 1m Iron (4cm) + active (1cm) air + active (1cm) hadron shower muon This full structure is repeated Paul Soler A.Cervera ISS-CERN

16. 16 Combining NOvA + iron free Studies going on by the Valencia/Geneva group. Results this summer ? Iron (2cm) + active (4cm) air + active (1cm) hadron shower muon Liquid scintillator iron

17. 17 Conclusions Segmented magnetised detectors are the best option to study the golden channel Small   Iron detectors can measure it very well. But problems with CP A TASD detector would do it better  Large   In principle, no problems with iron, even for CP. To check !!! TASD is still good Problems with TASD: Magnetisation Low density: need larger detector Studies going on by several groups (talk by M. Ellis)