on storage ring and muon energy
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On storage ring and muon energy
IDS-NF plenary meetingRAL, UKSeptember 22-25, 2010
Walter Winter
Universität Würzburg
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Contents
Triangular shaped storage ring? Muon energy? Open issues (towards the RDR!?)
Discussion materialbased on
Agarwalla, Huber, Tang, Winter, in preparationVERY PRELIMINARY RESULTS!!!
Triangular-shaped rings
4
Assumptions (for triangle)
Working hypothesis:characteristics similar to racetrack ( cost!) Circumference: c=1609 m Curvature radius: r=78 m Isosceles triangle 2.5 1020 useful muons over s=600m: SF=1
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Theorems (1)
1. One can always build a triangular-shaped ring if c > 2r, indep. of detector locations
Proof: use inner circle = minimum „triangle“; then „pull apart“
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Theorems (2)
2. The worst case number of useful muon decays will be similar to the racetrack case (modulo curved sections)
Proof: Worst case looks like racetrack:
SF ~ 2 (all muons in that ring) * ½ ~ 1
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Geometry/efficiency
Examples:
1. RAL LNGS+Henderson: SF=1.38 (1510+7107 km)
2. CERN Pyhaselmi+Icicle creek: SF=1.00 (2290+7809 km)
3. RAL Slanic+INO: SF=0.95 (2112+7822 km)
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Considered sites/baselines
9
Considered combinations
Muon energy
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New ingredients
MIND re-analysis (Cervera, Laing, Martin-Albo, Soler, arXiv:1004.0358)
high backgrounds, especially at ~ 8 GeV (antinus) contamination (Donini, Gomez Cadenas, Meloni, arXiv:1005.2275)
peaks at low energies (good or bad?)
(reconstructed energy)
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Performance comparison
With new MIND analysis, performance is clearly worse(problem: CC BG)
Tau neutrinos improve sensitivity
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E-reoptimization
Example: RALband: second baseline varied
Some indication that in many cases sensitivity saturates at ~ 15 GeV
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Site-based results
Need L > 3000 km!!!
Open issues/discussion
(maybe more towards the RDR)
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Open issues: baselines
Long baseline not so critical (many options, exact choice not so relevant)
Short baseline: only one option close to 4000km found: JPARC-CJPL (China)No option between 4000km and 5000km
However: long enough baseline crucial for CPVNew sites neededCan one build the detector overground?
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Open issues: detector
Impact of new MIND analysis, which is in preparation?
Ways to reduce CC backgrounds (anti-nu)? Consistent analysis of contaminations
Near detectors/systematics MIND close to overground (previous slide)?
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Open issues: accelerator
Feasibility/ pros/cons triangular-shaped ring
Consider some accelerator components optional
Reasaonable spitting points for staging?
?
?
?
4.5-5 GeV?
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Open issues: costing
Possible ways to reduce cost? Triangular shaped ring (possibly with two
pipes) versus two racetracks? 12.6 GeV – 25 GeV FFAG optional?
Maybe: define system in a suitable way for energy upgrades, reflected in costing?
MIND overground???
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