TJR 10/30/031 MICE Beam rates Tom Roberts Illinois Institute of Technology 10/30/03

TJR 10/30/032 Outline

TJR 10/30/033 Idealizations Made Simulated using the Geant4 framework Normalization via both Geant4 and LAHET Beamline – Paul Drumm’s May 2003 Drawing –Quads have non-Maxwellian block fields (no fringe fields) –Bends have 2-D computed fringe fields, not 3-D, not measured –Solenoids have computed fields, not measured –Shielding of fringe fields by other magnets not included –For mainline analysis, no backgrounds (materials kill particles) Cooling Channel – Based on the MICE proposal –Pillbox RF cavities (with stepped Be windows) –Bellows windows for absorber and safety windows (slightly old design) –No backgrounds (materials kill particles, track μ + only) Detectors – Highly Idealized –Perfect Trackers Constructed of vacuum, 0 mm thick, placed at center of solenoid Measure {x,y,z,t,Px,Py,Pz} with the resolution of a float –No Cherenkov, TOF0, TOF2, or calorimeter (μ + selected by fiat)

TJR 10/30/034 MICE Beamline Layout Red line:Proton beam Green:Quad, D Blue:Quad, F Yellow:Bend Red:Decay Solenoid Light Blue:Diffuser1 (Proton beam bending not shown) (Proton beam shown starts at target)

TJR 10/30/035 MICE Cooling Channel Layout White:Diffuser1, TOF0,TOF1, TOF2 Yellow:Solenoids Red:RF Cavities Green:Absorbers

TJR 10/30/036 Task Flow of Rate Normalization Tune Beamline 10M Protons on Target LAHET 5M Protons on Target Geant4 (LHEP_BIC) Determine π + Acceptance (Pπ and Aperture) Select π + Cut on Pπ Weight into Aperture Select π + Cut on Pπ Weight into Aperture Generate 98M π + into Acceptance Track through Beamline and Cooling Channel Count Good μ + Compute Rate Using Beam Assumptions for p on Target Compute Rate Using Beam Assumptions for p on Target

TJR 10/30/037 Tune Beamline Tune B1 (central field, position) so 300 MeV/c π + go down the centerline Tune B2 (central field, position) so 200 MeV/c μ + go down the centerline Use Minuit to vary Q1,Q2,Q3 gradients to maximize μ + (Diffuser1) for a fixed set of π + from target Decay Solenoid held fixed at 3.0T

TJR 10/30/038 Particle Economics Generate 98,000,000 π + into beamline acceptance, track through beamline and MICE cooling channel with no LH 2 or RF –876,626 μ + at Diffuser1 –690,593 π + at Diffuser1 –10,559 good μ + (μ + at both Diffuser1 and TOF2) Geant4 Target Simulation: Generate 5M p into target –1.60 π + into beamline acceptance LAHET Target Simulation: Generate 10M p into target –4.53 π + into beamline acceptance ~30% discrepancy between LAHET and Geant4 normalizations; good agreement in Pπ distribution at 25 degrees For Singles Rates (only), generate 800,000,000 protons into target, get 2 μ + out.

TJR 10/30/039 Targeting Assumptions Target is 10mm long, 10mm high, and 1mm wide; Titanium Target “dips” 2mm vertically into the ISIS beam At our target, the ISIS beam has the area of a circle with radius 37.5mm At the edge, the ISIS beam has a density that is 0.1 times the average density (scraping makes it non-Gaussian) We have good target and good RF for 1ms per second The ISIS beam has 2.5·10 13 protons/bunch with a bunch rate of 1.5 MHz

TJR 10/30/0310 MICE Good μ + Rates LAHET Normalization: 83 Good μ + per second Geant4 Normalization: 59 Good μ + per second These particles occur during the 1 ms/second we have both good target and good RF. Further cuts on RF timing will be required. A “good μ + ” is a μ + at both Diffuser1 and TOF2 (i.e. π + and μ + decays after Diffuser1 are omitted).

TJR 10/30/0311 Effects of Diffusers on Good μ + Rates Diffuser1 Thickness (mm) Diffuser2 Thickness (mm) Highlighted cell is the MICE proposal

TJR 10/30/0312 Target Heating Average E loss per proton = 6.4 MeV Protons intersecting target per second = 1.7·10 12 Target motion factor: 10 (accounts for beam intercepted by target while moving into position) Beam halo and other backgrounds ignored Predicted heating: 17.4 Watts

TJR 10/30/0313 Singles Rates – Q1 Upstream Rate during the 1 ms/second of Good Target.

TJR 10/30/0314 Singles Rates – Q3 Downstream Rate during the 1 ms/second of Good Target.

TJR 10/30/0315 Singles Rates – Decay Solenoid Upstream Rate during the 1 ms/second of Good Target.

TJR 10/30/0316 Singles Rates – Decay Solenoid Downstream Rate during the 1 ms/second of Good Target.

TJR 10/30/0317 Singles Rates – Diffuser1 Rate during the 1 ms/second of Good Target. Low Statistics – only 2 mu+ and 2 pi+.