1. How to extract Neutrino Factory flux from IMD and neutrino elastic scattering? Near Detector Workshop, CERN, 30 July 2011 Paul Soler

2. 2 Near Detector workshop, CERN, 30 July 2011 Outline o Spectra at near detector of a neutrino factory o Outline method to extract fluxes at ND o Inverse Muon Decay o Muon-neutrino electron elastic scattering o Electron-neutrino electron elastic scattering o Combination of channels to extract fluxes

3. 3 Near Detector workshop, CERN, 30 July 2011 Spectra at Near Detector oNear Detector sees a line source (600 m long decay straight) oFar Detector sees a point source 1 km 100 m 2500 km ND FD Need to take into account these differences for flux measurement 100 m 1 km

4. 4 Near Detector workshop, CERN, 30 July 2011 o How to extract the neutrino factory flux from the measurements of IMD and nue elastic scattering? o Use channels with very small theoretical error in the cross- sections and measure them at near detector: –Inverse muon decay (Charged Current): –Elastic neutrino scattering: Neutral Current: Interference Charged Current/Neutral Current: o These processes have cross-sections about 10 -3 of total CC cross-section but can still expect ~10 6 events in a near detector at a neutrino factory Method

5. 5 Near Detector workshop, CERN, 30 July 2011 o Charged current processes: o Cross-section ~1.7x10 -41 E(GeV) cm 2, threshold = 11 GeV o We cannot distinguish between the two channels so we measure N 1 (E) + N 2 (E): Inverse Muon Decay

6. 6 Near Detector workshop, CERN, 30 July 2011 o Charged current processes: Inverse Muon Decay

7. 7 Near Detector workshop, CERN, 30 July 2011 o Neutral current processes: o Cross-section 0.16x10 -41 E(GeV) and 0.13x10 -41 E(GeV) cm 2 o We can only distinguish between the two channels since each come from a different muon decay:  Accuracy of cross-section depends on sin 2  W Muon-neutrino electron scattering

8. 8 Near Detector workshop, CERN, 30 July 2011 o Interference neutral and charged current processes: o Cross-section 0.96x10 -41 E(GeV) and 0.40x10 -41 E(GeV) cm 2 o We can only distinguish between the two channels since each come from a different muon decay:  Accuracy of cross-section depends on sin 2  W Electron-neutrino electron scattering

9. 9 Near Detector workshop, CERN, 30 July 2011 o So, if we consider the IMD and neutrino elastic scattering channels together we obtain: –For the NF decay: –We can extract the fluxes when we have IMD and elastic scattering: –Below 11 GeV we cannot resolve since we only have N 3 +N 6 Combination of all channels

10. 10 Near Detector workshop, CERN, 30 July 2011 o So, if we consider the IMD and neutrino elastic scattering channels together we obtain: –For the NF decay: –We cannot resolve the two fluxes because they are together:  So, we can only resolve the fluxes when we are in an energy bin in which we have both IMD and elastic scattering for  - decay. For  + decay, we cannot resolve fluxes with this method – maybe we can do ratio of  + /  - or fit shapes o Are there any other neutrino processes that we can use? o We need to look at these possibilities to extract final fluxes Combination of all channels

11. 11 Near Detector workshop, CERN, 30 July 2011 o Method for extracting neutrino fluxes at NF relies on using channels in which cross-sections are known very well theoretically o Channels identified include: –Inverse Muon Decay –Muon-neutrino electron elastic scattering –Electron-neutrino electron elastic scattering  Combination of IMD+neutrino elastic scattering works very well for  - decay above IMD threshold (11 GeV)  For  + decay cannot resolve two fluxes o Might have to rely on fitting shapes or other processes (quasi-elastic scattering?) Conclusions