“Conventional” neutrino beams : Target requirements

  • Published on
    22-Feb-2016

  • View
    40

  • Download
    0

Embed Size (px)

DESCRIPTION

Conventional neutrino beams : Target requirements. Phil Adamson 13 th January 2012. Anatomy of a neutrino beam. Primary proton bea m Beam window Target Produce ,K Focusing elements Horns sign-select pions. Decay volume + -> + Beam Absorber Absorb hadrons - PowerPoint PPT Presentation

Transcript

PowerPoint Presentation

Conventional neutrino beams: Target requirementsPhil Adamson13th January 2012fffffAnatomy of a neutrino beamPrimary proton beamBeam windowTargetProduce ,KFocusing elementsHorns sign-select pions

PASI neutrino requirements - Phil Adamson2

-+TargetFocusing Horns2 m675 m15 m30 m120 GeV protonsDecay volume+ -> + Beam AbsorberAbsorb hadronsMuons range out in rockNeutrinos leftfffff2IntroductionWill discuss the requirements on targets and target halls for high power neutrino beamsNOvA at 700kWLBNE at 700kWLBNE+Project X at 2.2MWLow energy beam with Project X?Discussion is mostly genericBrand-name advice also available in the roomPASI neutrino requirements - Phil Adamson3fffffAn example from NuMIPASI neutrino requirements - Phil Adamson

Solid consistent running delivered 3.2E20 protons to NuMI in FY10Scheduled summer shutdown4fffffAnnus HorribilisGot 2.2E20 in FY11, thanks to heroic efforts from target folks (and delay to future projects)Without target problems would have been 4E20PASI neutrino requirements - Phil Adamson

5fffffThis was NT06PASI neutrino requirements - Phil Adamson

Water cooling lines sprang leak after a few daysLimped on for a month until outer can failed

6fffffUptime is important!but uptime is a Heisenberg numberWhen you try to define it, it gets hard to measure NuMI example: downtime isTime removing broken target and installing new targetTime running at low intensity to try to extend life of dying target

PASI neutrino requirements - Phil Adamson7fffffDesign ImplicationsNeutrino experiments care about integrated neutrino flux over the years)New target design with 10% flux improvement?Great, but if it needs replacing twice a year at 2 weeks or so downtime each, you just lost.Yield per proton vs design conservatism Tristan this morningProbably guaranteed 4 weeks scheduled downtime per yearTarget hall maintenance in shutdown is freeReplace consumable targets etc.Otherwise, want target hall components to be quick to replace or robust

PASI neutrino requirements - Phil Adamson8fffffNeutrino FluxPASI neutrino requirements - Phil Adamson

For LBNE, oscillation maxima at 2.5 and 0.8 GeVMust place target inside horn (cf. NuMI LE)Also low energy (cf. BNB)

9fffffOff-axis this isnt true: NOAPASI neutrino requirements - Phil Adamson10

Off-axis, neutrino energy driven by angleAdjust focusing to optimize fluxTarget goes upstream of horn020fffffLBNE Flux optimizationPASI neutrino requirements - Phil Adamson11fffffPredicting FD spectraOscillation experiments have near detector to measure beamBut you cant put a near detector far enough away to make the beam look like a point source rather than a line source

PASI neutrino requirements - Phil Adamson

Depend on modelling beam for F/N pred12fffffPredicting FD spectraMINOS weights Fluka using ND data at different target positions & horn currentsT2K uses measured meson yields from NA61PASI neutrino requirements - Phil Adamson

13fffffConstraints from FD predictionPASI neutrino requirements - Phil Adamson14fffffTarget AlignmentProton beam scanned horizontally across target and protection baffleAlso used to locate hornsHadron Monitor and the Muon Monitors used to find the edgesMeasured small (~1.2 mm) offset of target relative to primary beam instrumentation.

Pulse Height in Chamber (arb.)targetbafflebaffletargetbafflebaffleGraphite protection baffleGraphite targetWater cooling line21.4 mm15.0 mm11.0 mm6.4 mmHorizontal FinTargetHornBaffleppPASI neutrino requirements - Phil Adamson15fffff15Harp on implementationAlignmentNeed beam-based alignment to be sure of what youve gotNuMI target hall moves when shielding blocks are installedThermal motionTarget, horns need features that can be located with beam scanMonitoring alignment whilst running would be greatHylen thermometer for NOvA will it survive 2MW?Particle yields must be insensitive to natural variation in proton beam positionMachine dependentNuMI has 100um RMSInsensitive is a function of the accuracy of the measurementIssue for balls?PASI neutrino requirements - Phil Adamson16fffffProton beam alignmentNeed to know/measure beam sigmaVariations greater than 100um are badNuMI has Ti SEM wires/foilsWont work for 2MWWill carbon fibre survive?Electron beam?PASI neutrino requirements - Phil Adamson17fffffWhats in your target?As mentioned, need target & horn model to extrapolate from near to far detectorTarget has to be the same from pulse to pulseDifferent from pbar or muon production target, where you dont care too much exactly what comes outFor neutrino beam, the target is part of the physics of the experimentDifficult to use liquid or powder target for this

PASI neutrino requirements - Phil Adamson18fffffNuMI 2nd target depletion ( ZXF-5Q amorphous graphite )NT-02 replaced when spectrum shift became too large.

Decrease as expected when decay pipe changed from vacuum to helium fillEach point in energy bin represents ~ 1 month running, time from 9/2006Gradual decrease in neutrino rate attributed to target radiation damage No change when horn 1 was replaced No change when horn 2 was replacedSpectrum recovered when new target was insertedPASI neutrino requirements - Phil Adamson19fffffWhats in your target?NuMI observed radiation damage to the graphite of target NT02 (change in neutrino yield)Effect modelled by removing target fins in MC at maximum dpa from MARS modelNuMI coped with a loss of yield of 10% with a much better than 1% effect on Near -> Far extrapolationWould prefer to replace a target before it got to that stateWant muon monitor able to track thisDont wait to integrate enough neutrino events to see issue.PASI neutrino requirements - Phil Adamson20fffffSecondary beam monitoringTarget hall is a hostile environmentWant multiple complementary beam monitors to distinguish between real effects and dying instrumentationHadron monitor downstream of decay pipeSurvivability at 2MW?Muon monitorsMuons and neutrinos come from same decaysCalibration, drifts, delta rays, Temperature rise in absorber is a great independent measureThis kind of monitoring feeds directly into experiments systematic error budgetPASI neutrino requirements - Phil Adamson21fffffProject X / LBNE beamLBNE beam still comes from Main InjectorNew RF system, but not much change53 MHz bunchesBunch length < 2ns sigma1.2s cycle time at 120 GeV0.75s at 60 GeV1.6E14 protons per spill3.3E11 protons per bunchFactor 4 increase over now2.3 MW

PASI neutrino requirements - Phil Adamson

3.5ns22fffffSummaryUptime (integrated neutrino yield)For a given target, integrated number of protonsIts probably worth paying a little pion yield for a more robust targetRobustness/fast replacementRepeatabilityTarget is the same each pulseAlignabilityTarget hall components can be aligned, and alignment monitored, with beam Radiation damageModel and monitorRedundant instrumentationIf you see an effect in hadron monitor and muon monitor, its more likely to be realAt 2.2MW, expect the unexpectedPlan & mitigate risks, butPASI neutrino requirements - Phil Adamson23fffff

E =

1 m

2

m2,K

E,K

1 + 22

Recommended

View more >