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

Shining Light on Neutrino Interactions Andrzej Szelc (University of Manchester)

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 F. Reines Cowan in 1956 (despite Pauli's fear of it interacting too weakly to be discovered). C. Cowan ● Neutrinos from extra-terrestial sources were discovered: the Sun and cosmic rays. ● Very quickly it was discovered that R. Davis Jr there are fewer neutrinos than constructing his expected. experiment in the Homestake mine ● This has now been confirmed to be a a result of n -oscillations. Super- Super-Kamiokande Collaboration Kamiokande Phys. Rev. Lett. 81, 1562–1567 (1998) 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 2

Measuring Neutrino Oscillations n l l ● In oscillation physics we usually start with one type of neutrino and measure how it changes into another. ● We can do this by detecting the new neutrinos Nucleon Nucleon (appearance) or registering the loss of original (disappearance). ● We know three neutrino flavors: n e , n m and n t . 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. 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 3

The Current State of Knowledge The neutrino model Our picture of Neutrinos in the “Unknown” standard model is physics almost complete. “Large” mixing angle q 13 opens the way to Short baseline ● measurements that measurements hint at could explain the oscillations matter – antimatter incompatible with 3 asymmetry in the neutrino model . Universe Tantalizing anomalies ● that could be interpreted as a new neutrino state – the “Known” sterile neutrino. physics At tension with results from MINOS+, DayaBay and IceCube. 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 4

Detecting neutrinos in a LArTPC proton ● Neutrino measurements are Muon difficult. ● Due to the photon n interaction backgrounds n e Charged p appearance is particularly challenging. ● The LArTPC and its bubble chamber-like proton data gives us strong n interaction background rejection tools. Charged p Muon 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 5

LArTPC Operation PMT 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 6

Neutrino interactions in LArTPCs ArgoNeuT data ADC 1 Run 650, Event 0 0 29167 Induction View ArgoNeuT data 0 Time ArgoNeuT data Wire - 2 5 g interactions 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 7

US based LArTPC Program Two Years ago, this was a reasonably accurate slide... 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 8

L A r T P C d e v e l o p me n t D e v e l o p me n t a n d p r o t o t y p i n g t h r o 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 o p l a t f o r m p r o g r a mme s M i c r o B o o N E S B N D S i n g l e - P h a s e D U N E R e f e r e n c e D e s i g n I C A R U S S B L 2 0 1 5 2 0 1 8 L B L 3 5 - t p r o t o t y p e p r o t o D U N E D U N E A l t e r n a t i v e D e s i g n 2 0 1 8 2 0 1 6 D u a l - P h a s e WA 1 0 5 : 1 x 1 x 3 m 3 P r o t o D U N E This is a somewhat d b l p h a s e simplified drawing... 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 9

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. 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 10

10/05/17 A. M. Szelc @ Birmingham HEP Seminar 11

LArTPC detectors (2) ● LArTPCs seem to do a good job using ionization charge. PMT ● Why do we care about scintillation light? 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 12

Scintillation Light ● Liquid argon is a prolific scintillator. ● The light is always there, complementary to the charge. ● This is the most active field of development in LArTPCs. 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 13

Scintillation Light in Argon Emission: Ar Ar Ar Ar Excited dimer state Two-component light, g 7ns + 1.3 us Photons are all ~128 nm – VUV Light consists of two components: fast and slow. Their relative amplitudes depend on ionization density (theory). E. Segreto (practice) the shape can be affected by transport, contamination and WLS effects (next slides) 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 14

Scintillation Light in Argon (2) Transport: ] s n / 2 5 m c [ Liquid argon is mostly transparent y t i g c 2 0 to its own scintillation. o l e v p u 1 5 o r g At longer distances effects like: Visible ● Rayleigh scattering ~55cm f( l ) 1 0 VUV ● absorption, e.g. on nitrogen ~30 5 m @2ppm N2 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0 7 0 0 begin to play a role. λ [ n m ] Note high refractive index ~1.5 3 × 1 0 and gradient of for VUV → 1 0 0 E E n n t t r r i i e e s s 3 3 7 7 4 4 5 5 4 4 6 6 0 0 M M e e a a n n 1 1 0 0 . . 1 1 3 3 relatively slow light. E E n n t t r r i i e e s s 6 6 6 6 3 3 0 0 7 7 1 1 0 0 R R M M S S 1 1 . . 5 5 8 8 8 0 Me Me a a n n 2 2 4 4 R R MS MS 0 0 . . 0 0 8 8 2 2 9 9 3 3 6 0 VUV Visible 4 0 2 0 0 0 5 1 0 1 5 2 0 2 5 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 15 v [ c m / n s ] g r o u p

Scintillation Light in Argon (3) Detection: Liquid argon is almost the only 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. 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 16

Scintillation Light in LArTPCs: trigger ● A scintillation burst during the beam gate gives an indication that a neutrino signal happened. ● Provides a “t 0 ” - necessary to calculate x-position. ● Needed to apply proton n interaction “x” corrections for loss of charge. Charged p Muon 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 17

Scintillation Light in LArTPCs: cosmic background removal ● LArTPCs on the surface see several cosmic rays in one readout frame. ● Need to match flashes to a charge deposition in the chamber. ● Allows rejecting backgrounds from cosmics and assign “t 0 ” to each event. 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 18

Scintillation Light in LArTPCs: timing ● LArTPCs are relatively slow M. Sorel JINST 9 (2014) P10002 detectors (1 frame is ~1ms). ● Improving timing resolution opens new physics possibilities: – Few 100ns: Tag Michel electron decays through timing – 1-2 ns: resolve beam bucket MiniBooNE structure – ? ns: beam exotics heavier than neutrinos. 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 19

Scintillation Light in LArTPCs: energy resolution R Acciarri et al. 2012 JINST 7 P01016 ● Quantity of scintillation light is complementary to charge. ● Registering both will improve energy 59.5 keV 241 Am peak LY @7phel/keV resolution. ● Knowing position will maximise precision. ● Largest benefits at lower energies, where TPC not as P. Benetti et al. (WARP), NIM A 574 (2007) 83 sensitive: Supernova neutrinos, nuclear effects, missing hadronic energy 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 20

PMTs vs SIPMs PMTs SiPMs ● Proven detector SiPMs: Relatively ● new on the block. technology in liquid Excellent ● argon. performance in ● Excellent timing liquid argon. Small voltage needed to resolution ~ ns. operate. ● e.g. Hamamatsu Small active size – ● R5912 8” PMTs need to be clever to avoid large ● Small channel/active channel number. area ratio. ● Non-negligible size, relatively high voltage. 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 21

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 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 22

The ARAPUCA light trap ● A way to enlarge the active surface without increasing number of channels. ● Use dichroic filters + 2 WLS Planned installation In SBND and protoDUNE E. Segreto & A. 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 23 Bergamini-Machado

From Theory to “Practice” 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 24

SBN Physics Phys. Rev. Lett. 110, 161801 (2013) ● Recalculation of reactor neutrino fluxes and analysis of sources in gallium experiments. ● MiniBooNE confirms its excess with the final data set. ● Very different experimental techniques are hinting at short baseline oscillations. ● Tension with other experiments, e.g. long- baseline. 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 25

SBN Program at Fermilab 10/05/17 A. M. Szelc @ Birmingham HEP Seminar 26