LBNF Ionization Detector Muon Monitors Jeremy Lopez University of - - PowerPoint PPT Presentation

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LBNF Ionization Detector Muon Monitors Jeremy Lopez University of Colorado 9 November 2016 LBNF Beamline Overview ND Target Decay Pipe Absorber & Muon Monitors Monitors downstream of absorber, upstream of ND Basically unlimited

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LBNF Ionization Detector Muon Monitors

Jeremy Lopez University of Colorado 9 November 2016

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LBNF Beamline Overview

Target Decay Pipe Absorber & Muon Monitors ND Monitors downstream of absorber, upstream of ND Basically unlimited statistics. Measurements limited by: 1) Detector performance 2) Absorber geometry (energy threshold, profile shaping, etc)

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pion muon neutrino

Muon Measurements

Reference design: 1 large muon alcove A single station for ionization detectors Get additional info from other detector types Ionization detector array

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Possible Technologies: Gas Ionization Counters

Used in T2K, NuMI, CNGS beamlines
Simple design (parallel plates with voltage

applied)

Reliable, don't age much
Gas needs to be refilled
Slow signal development – not great for timing
r studying beam substructure

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Possible Technologies: Diamond Detectors

Have been used in T2K, CNGS

beamlines but not in main muon monitor array

Very fast signals – good timing
May be less susceptible to pileup
More rad hard than other solid-state

detectors

Very expensive – can save some money

by producing detectors ourselves

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Possible Technologies: Silicon Photodiodes

Used in T2K beamline
Have many of the same advantages as

diamond

Need to be replaced fairly often
Commercial device
Low cost

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LBNF vs Other Beamlines

12.5 x 1012 POT / bunch, 6 bunches / spill
Muon rate in alcove ~ 10x NuMI alcove 1 and

2x T2K (at design power)

– Detectors must deal with harsher

environment, larger signals

– How will this affect signal linearity? – How long will detectors last?

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Tests in NuMI Alcove

Placed detectors in alcove 2 12 m or rock behind hadron absorber Muon rate ~ 1/4 that of alcove 1 ArXiv:1507.06690v2

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Diamonds in Alcove 2

3 diamonds placed

behind alcove 2 muon monitor

Cividec detectors,

previously used in CNGS

Data taken from Spring

2015 until present (work ongoing)

Diamonds

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Diamond Detector Signal

6 batches

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Zoom in on Signal

53 MHz bunches

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Some Initial Results

All work in progress

– Signal linearity – Resolution – Gain drift after detector HV turn on – Year-to-year gain variation – Signal shape

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Signal Linearity

Poor Statistics: Many single shots Good Statistics: Steady Beam April & May 2016 DUNE Work in Progress

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Signal Linearity

Nonlinearity <1% in region with good statistics
~4% looking over full data set

April & May 2016 DUNE Work in Progress

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Resolution

Gaussian fit: σ=0.3%
RMS: 0.4%
Ignoring nonlinearity & long term gain drift:

– Resolution much better than 1% for a single detector

May & June 2016 POT > 4x1013 DUNE Work in Progress

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Neutrino/Antineutrino Ratio

Antineutrino to

neutrino signal ratio is: 0.67±0.02

Detector and

alcove simulation with G4NuMI input: 0.68±0.03 (muon flux only, no energy loss)

Diamond Signal / POT

2016 DUNE Work in Progress

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Turn-On Effects: Short Term

After turning detector off for a weekend, see gain

rapidly increasing & then settling over first hour or so

Diamond Signal / POT [arb. units] Gain quickly increases when detector HV turned on DUNE Work in Progress

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Turn-On Effects: Long Term

Signal/POT continues to increase by several % over ~1

month after turning detector on

2016 Diamond Signal / POT [arb. units] DUNE Work in Progress

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Year to Year Variation

Note: Negative signals
Gain settles on different value: 2% drop from 2015 to 2016
Will this continue? Should continue if due to detector aging effects

2015

Diamond Signal / POT [arb. units]

2016

Diamond Signal / POT [arb. units]

DUNE Work in Progress DUNE Work in Progress

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Signal Shape

Shape doesn't

perfectly match proton signal

Significant fraction
f signal seems to

be associated with ~2 μs decay

– Muon

capture/decay?

– Materials

activation?

– Electronics? Signal per bunch [arb. units] Long decay Signal ramps up Slip stacking first 2 batches

DUNE Work in Progress

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Hardware Work

Have some silicon

photodiodes

Put in alcove 2, may help

resolve questions about signal shape

Working on building a diamond detector from

a bare diamond at CU

May be much more cost-effective than

prepackaged detectors

New diamond, different electronics – see how

performance compares to commercial devices

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Conclusions

Muon monitoring at LBNF will be more

challenging than at existing beams due to much larger fluxes

Solid-state detectors offer many possible

advantages over more standard gas detectors, but also may have some drawbacks

We have experience operating detectors in a

beamline, are working on constructing our own detectors to test at NuMI