1. Neutrino-CH 19 October 2006 Alain Blondel HARP and K2K 1. The K2K experiments 2. beam related uncertainties 3. HARP and results 4. K2K and results 5. conclusions

2. Neutrino-CH 19 October 2006 Alain Blondel JPARC- ~0.6GeV beam 0.75 MW 50 GeV PS (2009  ) Kamioka J-PARC SK: 22.5 kt Phase II: 4 MW upgrade Phase II HK: 1000 kt K2K ~1.2 GeV beam 0.01 MW 12 GeV PS (1999  2005) (1999  2005) K2K & T2K

3. Neutrino-CH 19 October 2006 Alain Blondel K2K ran 1999-2001 2003-2004 12 GeV protons WBB flux X cross-sections poorly known from first principles measured in near detectors: Most useful turned out to be -- scibar (water + scint) -- MRD

4. Neutrino-CH 19 October 2006 Alain Blondel Far flux different from near flux (solid angle) neutrino cross-sections poorly known at low energies near detector is also a cross-section measurement device, PROVIDED FLUX IS KNOWN ==> hadron production measurements far/near ratio

5. Neutrino-CH 19 October 2006 Alain Blondel Hadron production on nuclear targets is a) complicated b) uninteresting for hadronic physics c) difficult to measure well d) absolutely mandatory for neutrino beam experiments ==> data are sparse and Monte-Carlos are very uncertain measure!

6. Neutrino-CH 19 October 2006 Alain Blondel HARP approved 2000 built in 17 months run sept. 2001 -> nov 2002 10 6 triggers at each of these settings Beam line PID Forward detectors --> neutrino beams - K2K, - Miniboone, - atmospheric, - Low energy SPL superbeam Large Angle detectors -->neutrino factory

7. Neutrino-CH 19 October 2006 Alain Blondel

9. HARP Beam counters: identify and count incoming particles define beam particle impact in target + empty target runs to subtract effect of non-target material and count composition in electrons and muons

10. Neutrino-CH 19 October 2006 Alain Blondel  K p TOF for p=2+-0.25N cherenkov for p below pion threshold HARP forward electrons hadrons electrons hadrons Calorimeter E/p and E(1st layer)/E for p above pion threshold

11. Neutrino-CH 19 October 2006 Alain Blondel

12. Uni-Ge: A.B, Borghi, Campanelli, Cervera, Gilardoni, Graulich, Morone, Prior, Schroeter Figure 9 Muon neutrino fluxes in the K2K experiment as a function of neutrino energy E, as predicted by the default hadronic model in the K2K beam Monte Carlo simulation (dotted histograms),and by the HARP  + production measurement (filled circles with error bars). Left: unit-area normalized flux predictions at the K2K near (top) and far (bottom) detector locations,  near and  far ; right : the far – to – near flux ratio (empty squares with error boxes show the K2K model results), showing the precision improvement brought by the HARP data.

13. Neutrino-CH 19 October 2006 Alain Blondel no oscillation flux*0.6 best osc. fit reconstructed « single ring » Quasi-elastics in SuperKamiokande ==> spectral shape + normalization show oscillation K2K final results (using HARP input, 4.1 -> 4.4  C.L. improved by factor 3) arXiv:hep-ex/0606032 v2 sept 06 (Blondel, Borghi, Cervera, Schroeter) + papers on  0 production and quasi-elastics

14. Neutrino-CH 19 October 2006 Alain Blondel

15. Large angle analysis

16. Neutrino-CH 19 October 2006 Alain Blondel

18. 1/p d 0 *sign

19. Neutrino-CH 19 October 2006 Alain Blondel

22. cryogenic H2 target

23. Neutrino-CH 19 October 2006 Alain Blondel

26. HARP large angle S. Borghi

27. Neutrino-CH 19 October 2006 Alain Blondel 0.3<  MeV  p   pi+ pi-  GeV is not a bad energy! HARP prelim Optimization of proton accelerator energy for the neutrino factory proton driver simulations (2005) data (2006) caution! these results are not obtained exactly in the same kinematic domain HARP prelim.

28. Neutrino-CH 19 October 2006 Alain Blondel   e search in K2K one candidate event found

29. Neutrino-CH 19 October 2006 Alain Blondel CONCLUSIONS -- Starting from HARP, we are building up an increasingly strong EU and CH contribution to the Japanese Long-baseline neutrino programme -- K2K confirmed the existence of oscillations with an accelerator neutrino beam first search for   e appearance -- Hadroproduction measurement have shown to be i) difficult and ii) important for understandng of oscillation experiments. -- The HARP data have been used successfully to improve the K2K oscillation result will be crucial for the upcoming miniBoone result will allow a firm conclusion on the choice of the energy for the CERN high power proton accelerator