1. TJR August 2, 2004MICE Beamline Analysis1 MICE Beamline Analysis JUNE04 Including a proposal for a JUNE04A Configuration Tom Roberts Illinois Institute of Technology

2. TJR August 2, 2004MICE Beamline Analysis2 JUNE04 Beamline Design Same basic physical layout as MAR04, with minor changes (e.g. downstream iron shield) Corrects many deficiencies of earlier designs JUNE04 still has problems: –Beam distributions are not all as desired (see below) –TOF0 singles rate is ~10 MHz –Good mu+ rate is only about half of the desired 600 ev/sec This talk discusses my analysis of a number of suggestions to address these problems. I propose a JUNE04A design that both reduces the TOF0 singles rate and increases the good mu+ rate

3. TJR August 2, 2004MICE Beamline Analysis3 JUNE04 Layout TOF0 TOF1 Ckov1 Iron Shield TOF2 Ckov 2Cal ISIS Bea m Diffuser

4. TJR August 2, 2004MICE Beamline Analysis4 JUNE04 Beamline Design – Properties AttributeValue pion momentum350 MeV/c muon momentum250 MeV/c Diffuser Thickness (Pb)8 mm Design emittance after Diffuser, for 1% Δp/p y-y’ 6 π mm-rad x-x’ >10 π mm-rad g4bl/ecalc9f emittance after Diffuser, full momentum interval 14.8 π mm-rad Good mu+ rate350 ev/sec TOF0 Singles9.9 MHz

5. TJR August 2, 2004MICE Beamline Analysis5 Observations on overall beam distributions, JUNE04 Average Momentum After Diffuser: 250MeV/c => ~ 236.5MeV/c Narrow-momentum (+/-1% ~ 236.5MeV/c): Beam OK yy' 6pi & well matched xx' larger distribution (improvable with quad optics) 236.5MeV/c Peak Momentum > 236.5MeV/c ! ☺  yy' ≥10pi & not well matched xx' large distribution, ≠ 0 & not well matched Good for Amplitude vs p correlation Overall beam distribution: Suffers from a few aberrations Narrow-momentum Beam OK Full beam Still needs attention ☺ Narrow momentum region

6. TJR August 2, 2004MICE Beamline Analysis6 Suggested Improvements Raise the pion momentum in the beamline oimprove π/μ separation in B2 oReduce TOF0 singles by eliminating πs oSlight increase in pion production Move TOF0 downstream of Q5, or downstream of Q6 oReduce TOF0 singles oReduce effect of multiple scattering in TOF0 oRequires moving TOF1 downstream of Q9, and an analysis that the pi/mu discrimination is still OK (below) Use thinner counters for TOF0 and TOF1 oReduce effect of multiple scattering in TOF0 and TOF1 -Consider changing the tune from FDF in Q4-6 to DFD oSteer more pions into the Q4 iron, and away from TOF0 oPerhaps also DFD in Q7-9 oMay be able to better balance the vertical and horizontal emittances (better horizontal aperture control of the beam?) Included in this analysis and proposal for JUNE04A

7. TJR August 2, 2004MICE Beamline Analysis7 Evaluation Criteria At present we don’t know the targeting parameters we will achieve, and basically must make an educated guess of what the overall rates will be. In practice, the target will have an adjustable insertion depth into the ISIS beam, and we will insert it until we are limited by one of the following: A.ISIS beam losses / activation of beamline elements B.Target heating C.Singles in TOF0 D.Tracker or DAQ event rate capacity The beamline design and tune cannot affect A, B, or D, and can only hope to optimize the good mu+ rate relative to TOF0 singles. The criteria I have used is to maximize the good-μ + rate and to minimize TOF0/good-μ +, both for a given set of 10M target π +. Remarkably, these two criteria are compatible.

8. TJR August 2, 2004MICE Beamline Analysis8 Proposed JUNE04A Layout Moved, Thinner, TOF0 New Iron Shiel d (TOF1 and its iron shield are symmetrical with TOF2, except for the Diffuser) Pπ = 425 MeV/c Moved, Thinner, TOF1

9. TJR August 2, 2004MICE Beamline Analysis9 Comparison of JUNE04 and Proposed JUNE04A AttributeJUNE04JUNE04A π momentum (B1)350 MeV/c425 MeV/c μ momentum (B2)250 MeV/c TOF0 positionDownstream of Q4Downstream of Q6 TOF1 PositionDownstream of Q8Downstream of Q9 TOF total thickness2 inches1 inch Upstream iron shieldNoneSame as downstream TOF0 to TOF1 distance8.5 meters7.8 meters [1] TOF0 Singles9.9 MHz3.8 MHz Good μ + rate350 ev/sec512 ev/sec Design Emittance6 π mm-rad [2] g4bl/ecalc9f emittance14.8 π mm-rad11.9 π mm-rad [1] π/μ/e discrimination in TOF1-TOF0 presented below. [2] Narrow-momentum beam, no multiple-scattering from TOF0 and TOF1, horizontal emittance much larger. Reasonably consistent with ecalc9 value.

10. TJR August 2, 2004MICE Beamline Analysis10 JUNE04A π/μ/e Discrimination in TOF1-TOF0 A major change in the JUNE04A design is the reduction in distance between TOF0 and TOF1, so we must verify that π + can still be cleanly separated from μ + There are no protons – TOF0 stops >99% of them in this momentum range Using Tracker1 to measure P tot, the perfect-resolution graph looks fine: Perfect TOF and Tracker Resolution A Q4-filling Gaussian beam with equal numbers of π +, μ + and e + No correction for E loss in the Diffuser GoodParticle = TOF0 & TOF1 & Tracker1 Still present: –Variations in path length –Variations in E loss (Diffuser)

11. TJR August 2, 2004MICE Beamline Analysis11 Estimated TOF and Tracker Resolutions The resolution in P z depends strongly on P perp, and is given in Fig 3.9 of the proposal; it is modeled here: From the proposal, TOF0 and TOF1 are estimated to have resolutions of 50 ps, giving a resolution of 70.7 ps for TOF1-TOF0. From the proposal, Tracker1 is estimated to have a resolution in P perp of 0.12 MeV/c.

12. TJR August 2, 2004MICE Beamline Analysis12 JUNE04A π/μ/e Discrimination, with Estimated Gaussian Resolutions in P perp, P z, and TOF

13. TJR August 2, 2004MICE Beamline Analysis13 Conclusions about JUNE04A Straightforward modifications to JUNE04 provide significant improvements in performance: –TOF0 singles reduced by a factor of ~2.5 –Good μ + rate increased by a factor of ~1.5 –Input emittance slightly reduced The reduction in TOF0 to TOF1 distance is OK – we still have good π/μ/e discrimination Reducing TOF0 and TOF1 to 1 inch total thickness improves the rate of good μ + Still need a design iteration: –Improve horizontal distributions –Correct the overall emittance –Tune the Decay Solenoid field (better π focusing and separation from μ)

14. TJR August 2, 2004MICE Beamline Analysis14 Comment on MICE Targeting Ti 1 mm wide, 10 mm thick, variable depth 10 mm wide, 1 mm thick, variable depth Current Baseline Possible Change There clearly is a multiple-scattering angle, and an energy loss, below which protons intersecting the target will not be lost. Because of this, it may be appropriate to rotate the target 90 degrees, so it is 10 mm wide and 1mm in length. While ~10 times more protons will intersect the target, perhaps only those that strongly interact will be lost. With everything else equal, we will adjust the depth so the number of strongly-interacting protons will be the same, independent of orientation. This might reduce ISIS losses, while not significantly affecting either the target heating or the MICE muon rates. ISIS Beam ISIS Beam

15. TJR August 2, 2004MICE Beamline Analysis15 Comparison of 1mm and 10mm Target Thicknesses Clearly the 1mm-thick orientation has much less impact on individual ISIS protons than does the 10mm-thick orientation. Evaluating whether or not this target rotation will reduce ISIS losses requires an analysis using the ISIS beam properties and lattice. Multiple ScatteringEnergy Loss