Shining Light on Neutrino Interactions Andrzej Szelc (University of - - PowerPoint PPT Presentation

Shining Light on Neutrino Interactions

Andrzej Szelc

(University of Manchester)

10/05/17

• A. M. Szelc @ Birmingham HEP Seminar

2

A short history of Neutrinos

• The neutrino was proposed in 1930

by W. Pauli to save energy conservation in b-decays.

• It was discovered by Reines and

Cowan in 1956 (despite Pauli's fear

• f it interacting too weakly to be

discovered).

• Neutrinos from extra-terrestial

sources were discovered: the Sun and cosmic rays.

• Very quickly it was discovered that

there are fewer neutrinos than expected.

• This has now been

confirmed to be a a result of n-oscillations.

• C. Cowan
• F. Reines
• R. Davis Jr

constructing his experiment in the Homestake mine

Super-Kamiokande Collaboration

• Phys. Rev. Lett. 81, 1562–1567 (1998)

Super- Kamiokande

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Measuring Neutrino Oscillations

Nucleon nl Nucleon l

• In oscillation physics we usually start with one type
• f neutrino and measure how it changes into

another.

• We can do this by detecting the new neutrinos

(appearance) or registering the loss of original (disappearance).

• We know three neutrino flavors: ne, nm and nt . We

tell them apart by the effect of their “Charged Current” interactions.

• By changing the energy of neutrinos and the

distance of observation we can address surprisingly different questions.

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The Current State of Knowledge

The neutrino model

Our picture of Neutrinos in the standard model is almost complete. “Large” mixing angle q13 opens the way to measurements that could explain the matter – antimatter asymmetry in the Universe

“Known” physics

• Short baseline

measurements hint at

• scillations

incompatible with 3 neutrino model.

• Tantalizing anomalies

that could be interpreted as a new neutrino state – the sterile neutrino. At tension with results from MINOS+, DayaBay and IceCube.

“Unknown” physics

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Detecting neutrinos in a LArTPC

• Neutrino

measurements are difficult.

• Due to the photon

backgrounds ne appearance is particularly challenging.

• The LArTPC and its

bubble chamber-like data gives us strong background rejection tools.

Muon proton Charged p n interaction Muon proton Charged p n interaction

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LArTPC Operation

PMT

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Neutrino interactions in LArTPCs

Wire 1 Time ADC

• 2

5

Run 650, Event 29167 Induction View

ArgoNeuT data g interactions ArgoNeuT data ArgoNeuT data

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US based LArTPC Program

Two Years ago, this was a reasonably accurate slide...

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L A r T P C d e v e l

• p

me n t

D e v e l

• p

me n t a n d p r

• t
• t

y p i n g t h r

• u

g h t h e F e r mi l a b S B N a n d C E R N n e u t r i n

• p

l a t f

• r

m p r

• g

r a mme s

D U N E A l t e r n a t i v e D e s i g n WA 1 5 : 1 x 1 x 3 m

3

2 1 6 2 1 8

P r

• t
• D

U N E d b l p h a s e

D u a l

• P

h a s e

3 5

• t

p r

• t
• t

y p e I C A R U S M i c r

• B
• N

E D U N E R e f e r e n c e D e s i g n

2 1 5

p r

• t
• D

U N E

L B L S B L S i n g l e

• P

h a s e

S B N D

2 1 8 This is a somewhat simplified drawing...

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DUNE

40 kT of liquid argon at SURF (South Dakota) A huge effort going on now to design and build. Starting with protoDUNE prototype at CERN.

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• LArTPCs seem

to do a good job using ionization charge.

• Why do we

care about scintillation light?

PMT

LArTPC detectors (2)

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Scintillation Light

• Liquid argon is a prolific

scintillator.

• The light is always there,

complementary to the charge.

• This is the most active field
• f development in

LArTPCs.

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Scintillation Light in Argon

Emission:

Ar Ar Ar Ar Excited dimer state

Photons are all ~128 nm – VUV

g Two-component light, 7ns + 1.3 us

• E. Segreto

Light consists of two components: fast and slow. Their relative amplitudes depend on ionization density (theory). (practice) the shape can be affected by transport, contamination and WLS effects (next slides)

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Scintillation Light in Argon (2)

Transport:

g

Liquid argon is mostly transparent to its own scintillation. At longer distances effects like:

• Rayleigh scattering ~55cm f(l)
• absorption, e.g. on nitrogen ~30

m @2ppm N2 begin to play a role. Note high refractive index ~1.5 and gradient of for VUV → relatively slow light.

[ n m ] λ

1 2 3 4 5 6 7

g r

• u

p v e l

• c

i t y [ c m / n s ]

5 1 1 5 2 2 5 E n t r i e s 3 7 4 5 4 6 M e a n 1 . 1 3 R M S 1 . 5 8

[ c m / n s ]

g r

• u

p

v 5 1 1 5 2 2 5 2 4 6 8 1

3

1 ×

E n t r i e s 3 7 4 5 4 6 M e a n 1 . 1 3 R M S 1 . 5 8 E n t r i e s 6 6 3 7 1 Me a n 2 4 R MS . 8 2 9 3 E n t r i e s 6 6 3 7 1 Me a n 2 4 R MS . 8 2 9 3

Visible VUV VUV Visible

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Scintillation Light in Argon (3)

Detection:

Liquid argon is almost the

• nly thing transparent to its

scintillation. Detection is challenging – most often need to use Wavelength shifting compounds, like TPB. Can deposit WLS on Light detection components or inside the detector. VUV sensitive SiPMs prototypes have appeared very recently.

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Scintillation Light in LArTPCs:

trigger

• A scintillation burst

during the beam gate gives an indication that a neutrino signal happened.

• Provides a “t0” -

necessary to calculate x-position.

• Needed to apply

corrections for loss of charge.

Muon proton Charged p n interaction “x”

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Scintillation Light in LArTPCs:

cosmic background removal

• LArTPCs on the surface

see several cosmic rays in

• ne readout frame.
• Need to match flashes to a

charge deposition in the chamber.

• Allows rejecting

backgrounds from cosmics and assign “t0” to each event.

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• LArTPCs are relatively slow

detectors (1 frame is ~1ms).

• Improving timing resolution
• pens new physics possibilities:

– Few 100ns: Tag Michel electron

decays through timing

– 1-2 ns: resolve beam bucket

structure

– ? ns: beam exotics heavier than

neutrinos.

Scintillation Light in LArTPCs:

timing

MiniBooNE

• M. Sorel JINST 9 (2014) P10002

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• Quantity of scintillation light is

complementary to charge.

• Registering both will improve energy

resolution.

• Knowing position will maximise

precision.

• Largest benefits at lower

energies, where TPC not as sensitive: Supernova neutrinos, nuclear effects, missing hadronic energy

Scintillation Light in LArTPCs:

energy resolution

R Acciarri et al. 2012 JINST 7 P01016 59.5 keV 241Am peak LY @7phel/keV

• P. Benetti et al. (WARP), NIM A 574 (2007) 83

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PMTs vs SIPMs

• Proven detector

technology in liquid argon.

• Excellent timing

resolution ~ ns.

• e.g. Hamamatsu

R5912 8” PMTs

• Small channel/active

area ratio.

• Non-negligible size,

relatively high voltage.

PMTs

• SiPMs: Relatively

new on the block.

• Excellent

performance in liquid argon. Small voltage needed to

• perate.
• Small active size –

need to be clever to avoid large channel number.

SiPMs

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SiPMs + coated bars

• WLS coated bars coupled

to SiPMs (current DUNE baseline design).

• SiPM timing not as good

as PMTs (Industry is working on this).

• Photon travel time in bar

adds to this.

• Work ongoing to

minimize attenuation in bars.

• Tested in 35ton –

prototype and test- stands.

• A. Himmel, FNAL

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The ARAPUCA light trap

• A way to enlarge the active

surface without increasing number of channels.

• Use dichroic filters + 2 WLS
• E. Segreto & A.

Bergamini-Machado Planned installation In SBND and protoDUNE

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From Theory to “Practice”

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• Recalculation of reactor

neutrino fluxes and analysis of sources in gallium experiments.

• MiniBooNE confirms its

excess with the final data set.

• Phys. Rev. Lett. 110, 161801 (2013)
• Very different experimental

techniques are hinting at short baseline oscillations.

• Tension with other

experiments, e.g. long- baseline.

SBN Physics

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SBN Program at Fermilab

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SBN Program at Fermilab

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Light Detection in SBND

• R&D is an important

part of the mission

• f SBND.
• Scintillation light is
• ne of the most

important aspects of this R&D.

• Plan to implement a

multi-technology setup .

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SBND Light Detection Systems

• Enhanced MicroBooNE

design.

• 60 8'' 14 dynode Ham

PMTs/TPC. DUNE-like light guide bars (secondary) SiPMs coupled to WLS covered light guide bars

• WLS covered reflector foils.
• Increase uniformity of light

collection.

• R&D for future experiments.

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Simulating light in argon (LArSoft)

• Argon is a prolific

scintillator, so at beam neutrino energies simulating each optical photon is not feasible.

• We use an optical lookup

library (developed by uBooNE) to mitigate this problem.

voxels Next slides, largely work by

• D. Garcia-Gamez, Manchester

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Considered confjgurations

PMT s PMT s

cathode Field cage TPB-coated foils: upstream + downstream up + down cathode

“Full coverage confjguration”

PMT s PMT s

cathode Field cage TPB-coated foils

“Cathode only confjguration”

PMT s PMT s

Field cage

“No foils/cathode confjguration”

array of PMT s in the simulations We use the symmetry of the system. Overshoot number of PMT s (11 x 14 PMT s / TPC 8’’ diameter) to be able to switch them On/Ofg

Only “2 TPC” simulation

Note: from now on, visible refers To light wavelength-shifted and reflected off of the foils, while VUV refers to light directly hitting the PMTs.

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Light Yield Uniformity

VUV Visible Total No foils Full Coverage Cathode

• nly

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Light Yields

Average number of photons/event/MeV (adding the signal in all the PMT s) vs X position (drift distance to the photocathode plane)

MC - Preliminary MC - Preliminary

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Calorimetry with Scintillation Light

For protons interacting inelastically a large fraction

• f the energy is lost to the

TPC. MC - Preliminary MC - Preliminary MC - Preliminary MC - Preliminary MC - Preliminary MC - Preliminary

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Timing

• To see if ~ns resolutions can be

achieved need to account for second

• rder effects, e.g. Rayleigh scattering.
• impossible to do using a lookup library

(memory) -> parametrization of arrival times.

• Assume we can model Argon

Scintillation timing (in principle

• ptimistic).

[ n m ] λ

1 2 3 4 5 6 7

g r

• u

p v e l

• c

i t y [ c m / n s ]

5 1 1 5 2 2 5 E n t r i e s 3 7 4 5 4 6 M e a n 1 . 1 3 R M S 1 . 5 8

[ c m / n s ]

g r

• u

p

v 5 1 1 5 2 2 5 2 4 6 8 1

3

1 ×

E n t r i e s 3 7 4 5 4 6 M e a n 1 . 1 3 R M S 1 . 5 8 E n t r i e s 6 6 3 7 1 M e a n 2 4 R M S . 8 2 9 3 E n t r i e s 6 6 3 7 1 M e a n 2 4 R M S . 8 2 9 3

Visible VUV VUV Visible

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Direct light (VUV) timing parametrization:

A combination of Landau and exponential functions fits practically every distribution

• f photon arrival times.

The fit parameters turn out to be monotonic functions of distance. MC - Preliminary MC - Preliminary MC - Preliminary MC - Preliminary MC - Preliminary

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Works for Visible Light too:

Cathode only configuration is much easier to model - Path of light easier to “predict”. MC - Preliminary MC - Preliminary MC - Preliminary MC - Preliminary MC - Preliminary MC - Preliminary

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Single PMT time resolution

Direct light Refmected light Note that flight time scales differently wrt distance for reflected/visible and VUVlight. MC - Preliminary

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Timing

MC – Preliminary No electronics effects High energy events Timing resolution depends on the quantity

• f arriving light (smaller

chance of missing photons coming in) MC - Preliminary

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Effects on timing constants

Fast component life time changes as a function of distance. MC - Preliminary Will affect triggers focusing on the fast component

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Position Resolution

• The high density of PMTs in SBND allows

reasonable position reconstruction with light

• nly.
• It cannot be as good as the charge

information, but it is fast. And it allows tagging events.

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• D. Garcia-Gamez

MC - Preliminary

Y-Z Positional Resolution

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X-drift position resolution

• If able to differentiate

VUV from Visible (re- emitted) possible to get position in x on the fly.

• Additional information,

crucial for disentangling multiple events in the same frame.

• Could decide to readout

just parts of detector.

New idea for LArTPCs!

With TPB coated foils MC - Preliminary MC - Preliminary

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39Ar – how big of a problem is it really?

• 39Ar is a beta- emitter with

an end point at 565 keV. average energy of electron ~ 236 keV

• Measured rate is 1Bq/kg.
• Could it
• verwhelm

the trigger?

arXiv:astro-ph/0603131v2

MC - Preliminary

• C. Hill,

Manchester

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What simulations can tell us

• Simulations show that a High LY light detection

system can help determine timing, calorimetry and position resolution.

• Adding WLS-covered reflector foils improves the
• verall performance of the system.

MC - Preliminary MC - Preliminary

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From “Practice” to Reality

Or: Back From the Future

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The LArIAT testbeam experiment is running in MCenter – allows long term occupation (as opposed to MTest).

Fermilab Testbeam Facility Fermilab Testbeam Facility

Main injector protons

Main Injector One 4s long spill per minute Secondary beam max 300k particles/spill

Secondary

MTest MCenter

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LArIAT Beamline

We will use a Tertiary beam (Similar to

MINERvA beam test). We want to study charged particles in the energy range relevant for future neutrino experiments. We can tune their energy by adjusting the parameters of the beamline,

Tertiary Beam at MCenter

Particles from ν interactions

NuMI LE on-axis

Tertiary Beam composition

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Time Projection Chamber

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• LArIAT is an excellent

test-bed for new ideas, like WLS – covered

• foils. .

LArTPC

LArIAT Light Readout

Applying TPB to the reflective foil that will line the inside of the LArIAT TPC Two cryogenic PMTS

• one 3” high QE (30%)
• one 2” standard QE

(20%)

+3 SiPMs Wavelength shifting reflector foil

Hamamatsu R11065

• First test of TPB

coated reflector foils in a running TPC (at beam neutrino energies).

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• I

n f a c t , t h e t

• l

s w e r e d e v e l

• p

e d f

• r

L A r I A T fj r s t , a n d a d a p t e d f

• r

S B N D .

• Using the same simulation

tools as SBND

L A r I A T P h

• t
• n

M C L Y = 1 4 . 1 p e / M e V

T

• p
• d
• w

n v i e w S i d e v i e w

L A r I A T P h

• t
• n

M C L Y = 6 . 2 p e / M e V

T

• p
• d
• w

n v i e w S i d e v i e w

Beam Direction Beam Direction

Excellent uniformity in the detector. Two full runs completed (Not all PMTs were always

• n).

Data analysis in progress.

• W. Foreman

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Validating the Simulation

• Simplest topology

– easy to understand.

• Great to test

predictions vs reality.

• Data agrees with

MC predictions (in progress).

μ

+ /

• L

A r I A T P r e l i m i n a r y T h r

• u

g h

• g
• i

n g μ E T L ( 2 ” ) P M T

P . K r y c z y n s k i

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W. F

• r

e m a n | U C h i c a g

• T

P B

• c
• a

t e d E T L P M T u n d e r a U V l a m p ( p r i

• r

t

• “

R u n 2 b ” )

• Well known energy spectrum.
• Great to perform calibrations.
• Need scintillation light to trigger.

R e a l

• t

i m e t r i g g e r i n g

• n

M i c h e l e ’ s f r

• m

s t

• p

p i n g c

• s

m i c μ ’ s u s i n g l i g h t s i g n a l s μ

+ /

• (

a t r e s t ) → e

+ /

• +

ν

μ

+ ν

e

μ

+ /

• e

+ /

• μ

+ /

• e

+ /

• Michel Electrons
• W. Foreman

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M C P r e d i c t i

• n

M C P r e d i c t i

• n

μ e n d p

• i

n t w i t h i n 1 5 c m

• f

T P C c e n t e r

• M

i c h e l

• c

a n d i d a t e s i g n a l s i n t e g r a t e d t

• g

e t P E s p e c t r u m

• D

a t a i n a p p r

• x

i m a t e a g r e e m e n t w i t h p r e l i m i n a r y M C

• G

i v e s c

• n

fj d e n c e i n M C

• p

r e d i c t e d L Y : 2 . 4 p e / M e V f

• r

2 ” E T L P M T ( R u n I )

Energy Calibration with Michels

End goal: combine charge + light to get full energy reconstruction.

• W. Foreman

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E a r l y r e s u l t s a g r e e w / r e c e n t m e a s u r e m e n t

1

( 8 5 4 ± 1 3 n s ) a n d t h e

• r

y p r e d i c t i

• n

2

( 8 5 1 n s )

1

( K l i n s k i h e t a l . , 2 8 )

2

( S u z u k i & M e a s d a y , 1 9 8 7 )

L I D I N E 2 1 5 P r

• c

e e d i n g s , J I N S T 1 1 C 1 3 7

6 5 ± 5 2 n s

( f r

• m

fj t r e s u l t , p r e l i m i n a r y )

9 1 8 ± 1 9 n s

D a t a s e t : ~ 1 2 d a y s

Physics with Michels

m- have a predicted 75% capture rate on argon nuclei (no Michel electron present). Neutrino-anti-neutrino discrimination possible?

• W. Foreman

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(Near) Future

• LArIAT analyses on using

light and combined light + charge for calorimetry, particle ID are finishing.

• The infrastructure needed

to manufacture the reflective foils for SBND is practically ready.

• Beginning to apply the

simulation tools to understand effects on DUNE physics (low energy events, SN neutrinos)

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Test run with mesh cathode

Prototype of SBND mesh cathode manufactured in Manchester was installed in LArIAT beginning of march. Will run with and without foils (change over in a few weeks).

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Fresh off the press!

LArIAT RUN III began in March. It is dedicated to testing the differences between 5mm and 3mm wire spacing. These are the first 5mm pitch events.

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Summary

• Scintillation light will be a powerful tool in

enhancing the physics goals of liquid argon neutrino detectors, from SBND to DUNE.

• There is still some uncharted territory and room

for new ideas and improvements.

• Using existing, or soon to be built detectors, like

LArIAT and SBND is a great way to test these new ideas and solutions.

• Stay tuned for results from LArIAT run III and

previous data.

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Thank You for your Attention