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MicroBooNE: LarSoft Simulation & PMT Response Tests

Jessica EsquivelAugust 6 2009Nevis Labs, Columbia University

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Outline/Acknowledgments

Mike Shaevitz Lesli Camilleri Willian Seligman Gary Cheng

MicroBooNE Overview SuperNova Neutrinos Hardware Software Future Work/Conclusion

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MicroBooNE Overview

Liquid Argon Time Projection Chamber

– Booster neutrino beam– Neutrinos from the Main

Injector(NuMi)

Primary Physics done is studying the low energy excess seen in MiniBooNE Published: “Unexplained Excess of Electron-Like

Events from a 1 GeV Beam”, PRL 102, 101802 (2009)

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MicroBooNE Overview

e+e-

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MicroBooNE Overview

Ionization electrons drift to 3 recording planes

– 2 Induction planes U, V: +- 60 to vertical

– 1 collection plane Y: vertical.

Electrons

Induction planes U VInduction planes U V

Collection plane Y

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MicroBooNE Overview

Scintillation light is collected by PMT's

– Used to determine the time when event occured

PMT's are coated with a Tetraphenyl-butadiene (TPB) to shift the scintillated light to visible light.

8” PMT

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Super Nova Neutrinos

Neutrino Signal is the first to emerge from a Supernova.– Can give information about the early stages of core

collapse

All Large LArTPC's should have the capability of collecting supernova neutrino data.– MicroBooNE is the beginning of large scale LArTPC's – Cold Electronics will reduce electric noise– LAr purity for longer drifts

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MicroBooNE Overview

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Hardware: PMT point response

First tests tested the point dependency on the PMT.

0°22.5°45°

67.5°

90°

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Hardware: PMT point response

Poor Correlation Unsteady Pulse

Generator

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Hardware: PMT response as a function of angle

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Hardware: Calculated vs Experimented

Fresnel's Equations shown below were used as a checkpoint calculations to make sure the data that was being collected was close to the calculated data.

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Hardware: Angle of Incidence Vs Relative Mean

Plot shows the calculated mean using Fresnel's Equations plus the data collected at three different points on the PMT

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Hardware: Angle of Incidence Vs. Relative Mean

Discrepancies calculated and measured data include:– Human error in measuring the angle of incidence.

2.65% on average over all the points 6.6% at point A 1.45% at point D 1.3% at point G

– Index of refraction of PMT was unknown, 1.5 was used for calculating purposes instead.

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Hardware: Photodetector response in electrostatic field

In the MicroBooNE experiment, the PMT’s will be exposed to an electric field of 500V/50cm– We are recreating this by building a blackbox with

two aluminum plates mounted 50cm away.

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Hardware: PMT E-Field Results

Turning on the +500V has no effect on the PMT pulse height

500V was then increased to 700V

– Still no effect The cathode is grounded

Therefore all outside field lines terminate on it.

– It acts as a Faraday cage

PMT was also reversed– Still no effect: There is an

electrostatic shield 16

LED

Pulser Oscilloscope+500V(Mesh)

50 cm

Ground(Cryostat)

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Software

The LArSoft software package has been run for NUE-e interactions with incoming energies of:

– 50MeV50MeV – 100MeV – 150MeV

The reason why LarSoft was run for such low energies was to be able to simulate supernova neutrinos which happen on a low energy scale.

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Software: Event Display

All events were shown in this form.

To extract information, a program was needed.

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Software

Histograms have been created for:– Incoming Neutrino/Anti-Neutrino Energy– Outgoing Lepton Energy– Outgoing Neutrino/Anti-Neutrino Energy– Theta between the Incoming Neutrino Vector and

Outgoing Lepton Vector– Number of Voxels relative to the incoming Energy– Number of Voxels vs the Energy of Electrons

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Software

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Software

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Software

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Software

Neutrinos are left-handed and electrons are as well.

Before colision, the angular momentum is zero.

Direction isn't important after collision because in any direction, angular momentum will be conserved.

This results in a flat neutrino energy distribution

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Software

Anti-Neutrinos are right-handed

Before Colision angular momentum is +1.

Direction is important because angular momentum needs to be conserved.

– Anti-neutrinos must emerge in the forward direction in the center of mass

This results in a peaked energy distribution.

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Software: Theta between Neutrino and lepton

Mean Theta in Degrees is: 13.32 degrees

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Software: Voxel

A Voxel is a 3D pixel that divides the energy deposited in the Liquid Argon into X, Y and Z cubes– These voxels are then what drifts to the simulated

wire chambers.

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Software

Energy: 50MeV Mean: 57.04Energy: 100MeV Mean: 115.6Energy: 150MeV Mean: 172.6

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Software

Plot shows the correlation between the Number of Voxels and the Energy of an Outgoing Electron

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Future Work

Understanding why some events are thrown out. Plot the electrons coming from an NUEbar-e interaction

separately from a NUE-e interaction. Plot Energy of Voxels vs Energy of Electron Do PMT response tests on the PMT being used in

MicroBooNE– Using a more sophisticated setup to reduce human error