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Collection system optimisation for SPL at 3.5 GeV

Collection system optimisation for SPL at 3.5 GeV. Antoine Cazes Laboratori Nazionali di Frascati November 14 th, 2006. Overview:. Interaction between proton beam and target. Simulation done with FLUKA 2002.4 and MARS Proton beam E k =2.2GeV, 3.5GeV , 4.5GeV , 6.5GeV et 8GeV Target

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Collection system optimisation for SPL at 3.5 GeV

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  1. Collectionsystem optimisation for SPL at 3.5 GeV Antoine Cazes Laboratori Nazionali di Frascati November 14th, 2006

  2. Overview:

  3. Interaction between proton beam and target. • Simulation done with FLUKA 2002.4 and MARS • Proton beam • Ek=2.2GeV, 3.5GeV, 4.5GeV, 6.5GeV et 8GeV • Target • Liquid mercury • Long : 30cm •  15mm • Normalization: 4MW • 1.1×1016pot/s@2.2GeV • 0.7×1016pot/s@3.5GeV

  4. Particle Producion p+ K+ p- K0 K- Ep(GeV) Ep(GeV) • 500 000 protons, Ek < 5GeV • at 2.2GeV : • 0.26 p+/s • 0.8 10-3 K+/s • at 4.5GeV : • 0.32 p+/s • 5.2 10-3 K+/s • at 3.5GeV : • 0.29 p+/s • 2.8 10-3 K+/s

  5. px/pz 20 mrad x 2 m px/pz 0,5 rad x 30 cm Horn optimisation • Neutrinos Factory • Decay tunnel = solénoïde • Momentum • At the target 2 105 pot nFact SB • Super Beam • 130km beam • Tunnel raduis

  6. B p+ • Pion transvers momentum p+ Horn + refl Only horn No focus p- p+ PT(GeV/c) PT(GeV/c) B Collector • 2 concentric horns • 300kA et 600kA • Conductor thickness : 3mm • Particles exit with large angle: • <qp> = 60°@2,2GeV • <qp> = 55°@3,5GeV • Target must be inside the horn.

  7. B1 B2 Horn design NuFact Note 138 x 2 optimisations studied : • En ~ 350MeV • (pp = 800MeV/c) • En ~ 260MeV • (pp = 600MeV/c) Oscillation Maximum

  8. En~300MeV 80 cm 140 cm 220 cm Horn design parameter Conductor thickness : 3mm horn : 300kAmps reflector : 600kAmps En~300MeV Ep~800MeV En~260MeV Ep~600MeV

  9. 47kW 34.0 kW 63kW (8mm Al) 13.6kW Energy deposition (Geant 3.2.1) 4MW, 2.2GeV +7kW from Joule effect Solution under investigation : reduce the Aluminium thickness (3mm Al) + strength rings. NuFact Note 134

  10. Decay Tunnel Parameters • Radius • modify acceptance • R=1m, 1.5m and 2m have been Tested • 1m 2m (L=40) • nm , nm +50% • ne , ne +50% to 70% • 2m seems better • Length • modify purity • L=10m, 20m, 40m and 60m have been tested. • 10m40m • nm , nm + 50% to 70% • ne , ne + 50% to 100% • 40m60m • nm , nm + 5% • ne , ne+ 20% • 40m seems better This results have been checked on sensitivity to q13 and dCP

  11. Flux computation • Low energy  Small boost  low focusing • Need a high number of events (~1015 evts!!!) • Use probability (M. Donega thesis approach) • Each time a pion, a muon, or a kaon is decayed by Geant, compute the probability for the neutrino to reach the detector • Use this probability as a weight, and fill an histogram with the neutrino energy • Gives neutrino spectrum.

  12. nm d q p+ 1 – b2 1 A m+ P = p a 4p (b cosa -1)2 L2 p Probability method …. Pions • Pion is tracked by Geant • When it decays, The probability for the neutrino to reach the detector is computed: • p+m+nm : (2-body decay) L : distance to detector A : detector surface To reach the detector: d = -a

  13. 1 A 2 1 1 – bm2 P =  4p L2 mm 1 + bmcosqm (bmcosr -1)2 * (f0(x) Pf1(x)cosqm)  * Probability method …. Muons • m+e+nmne • But muons have small decay probability. • for each muon • loop on the phase space (q,f,E) • compute decay probability e-x/gct • if it decays, compute probability for the neutrino to reach the detector : x = 2En/mm • P is the muon polarisation coming from the pion/kaon decay

  14. Probability method …. Kaons • Very few kaons : • kaon produced in the target is duplicated many times: ~100. • Decay using Geant • Choose the decay channel • Probability computed depending on the decay channel • 2 body decay • 3 body decay

  15. Neutrino flux @ 130km • 3.5GeV Kinetic proton beam • ~800MeV p focusing • ~300MeV neutrinos • 40m decay tunnel length • 2m decay tunnel radius

  16. Dm223 (eV2) En~260MeV 2.2GeV 3.5GeV 4.5GeV 8GeV 10-3 dCP = 0 sin22q13 10-3 Proton beam energy comparizon 5 year positive focussing 10 years mixte focussing (8y + and 2y -) Campagne, Cazes : Eur Phys J C45:643-657,2006 3.5GeV better !!!

  17. Conclusion • Choice of the beam energy is delicate • Tools exist to do another simulation • Proton interaction on target should be better with new version of fluka • Shape of the horns is crucial. • Technical feasability should be taken into account...

  18. That’s all folks !!!

  19. Project optimisation - Old result - New optimization 2yrs (+) 8yrs (-) • mixte Focalisation • Acces to dCP • To balance: • 20% positive • 80% négative Used values: dCP=0, q13=0, sin22q12=0.82, q23=p/4, Dm221=8.1 10-5, Dm231=2.2 10-3 5% precision on q12andDm221 Campagne, Cazes : Eur Phys J C45:643-657,2006 d’un factor 4 Gain on the sensitivity

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