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

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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

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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?

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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???