Measuring Neutrino Proper0es with Liquid Argon TPCs

Transcription

1 Measuring Neutrino Proper0es with Liquid Argon TPCs Oxford Seminar 13 October 2015 MaE Bass

2 INTRODUCTION 2

3 Outline Open ques0ons in Neutrino Physics Liquid Argon Time Projec=on Chambers LAr TPC Experiments 3

4 Exci0ng 0mes for Neutrino Physics and LAr TPCs David Nygren Time Projec=on Chamber Veljko Radeka Liquid Ioniza=on Detector 2015 APS DPF Instrumenta=on Award 4

5 From the Scien0fic Background on the Nobel Prize in Physics 2015 : Many other experiments attempt to determine the neutrino mass ordering, search for sterile neutrinos or measure the CP violating effects in the neutrino sector. The leptonic CP violation effects might have played a role for the baryon-antibaryon asymmetry in the universe through a mechanism called leptogenesis [73]. Hence, the discovery of neutrino oscillations has opened a door towards a more comprehensive understanding of the universe we live in. 5

6 Neutrino Oscilla0ons in brief > = X i U i i > 6

7 Open Ques=ons Parameters for three neutrino mixing: Amplitudes: µ 13, µ 23, µ 12 Mass- squared differences: Δm 2 31, Δm2 32, Δm2 21 Absolute masses unknown CP viola0ng phase: ± CP Open ques=ons: Is this three neutrino paradigm correct? Sterile ν? Is there CP viola0on in the lepton sector? What is the correct mass ordering (hierarchy)? arxiv: v2 7

8 How will Liquid Argon TPCs help? Neutrino oscillations over long-baselines: Neutrino mass ordering CP Violation Neutrino oscillations over short-baselines: Sterile neutrinos 8

9 Short- Baseline Neutrino Program at FNAL A comprehensive, LAr TPC based, program at Fermilab to: Study short- baseline neutrino oscilla=ons with high significance Perform R&D of the LAr TPC detector technology needed for future kt- scale LAr TPCs Three LAr TPCs in the Booster Neutrino Beam- line (BNB) 100 m ~2 years 470 m NOW! 600 m ~2 years 9

10 Making & Detec0ng a Neutrino Beam Proton Beam Target/horn Decay Region Dirt Detector 10

11 Electric field, ~500 V/cm, is setup by cathode plane Interac=ons in LAr produce ioniza=on electrons and photons Prompt scin=lla=on light (128 nm) reaches the PMTs first Wavelength shim (fibers, plates, coa0ng on walls of TPC, etc) to readout in PMTs Due to electric field, electrons drim, at mm/us, to anode plane where they induce charge in the induc=on planes (x2) and are collected on the collec=on plane No charge amplifica0on - > charge readout is propor0onal to deposited energy 11

12 Why LAr? Lots of ioniza=on electrons, ~6,000e - /mm for a MIP Transparent to its own copious, ~5,000 γ/mm for a MIP, scin=lla=on light at 128 nm Pure LAr (~0.1 ppb) will allow electrons to drim long distances Withstands large HV drim electric fields before breakdown Cheap, easy to obtain, 1% of atmosphere is Ar 40 12

13 e/γ Separa0on LAr TPCs can dis0nguish between e andγby Topology: gap between vertex andγ Energy deposi=on : 1 MIP vs 2 MIP Right: average de/dx in first 24 mm in an LAr test experiment Look the same in Cherenkov detectors 13

14 MicroBooNE 80 t ac0ve mass LAr TPC 8256 wires in 3 planes One ver0cal Two oriented at ±60 UV laser calibra0on system 32 PMT light collec0on system 14

15 Data from MicroBooNE MicroBooNE is in the commisioning phase now. Beam expected soon! Charge that reaches the wire (ADC) as color as a func0on of : =me (y- axis) wire number (x- axis) Cosmic EM Shower 15

16 Data from MicroBooNE Charge that reaches the wire (ADC) as color as a func0on of : =me (y- axis) wire number (x- axis) Cosmic Stopping muon 16

17 Data from MicroBooNE By combining data from the different wire- planes, can reconstruct 3D views. 17

18 Expected Physics Results So what physics can we do with a LAr TPC? Neutrino Oscilla0ons Neutrino Interac0ons Not covering Supernova neutrinos Atmospheric neutrinos Proton Decay 18

19 SBN Oscilla=ons arxiv: v1 MC MC MicroBooNE will look for an excess of ν e like events Some evidence of a signal from previous experiments (e.g. LSND and MiniBooNE) Assuming the MicroBooNE excess is e- like then ν μ - >ν e oscilla=on may explain the excess The full SBN program can exclude the global best- fits and the LSND signal region at 5σ 19

20 DUNE The Deep Underground Neutrino Experiment Mul=ple 10 kt LAr TPCs at the 4850 level at the Homestake mine 1.2 MW beam upgradeable to 2.4 MW at FNAL Determine the neutrino mass hierarchy Measure possible CP viola=on in the lepton sector DUNE CDR1- R 20

21 Neutrino Interac0ons in LAr Few measurements exist of neutrino interac0ons on LAr Fortunately, this will change soon! 21

22 An0cipated Results: MicroBooNE MicroBooNE sits in the wide- band, ~800 MeV, BNB beam at FNAL Over 3 years, 6.6e20 POT the 87 t ac0ve volume LAr TPC will see a large set of inclusive and exclusive interac=ons MicroBooNE 22

23 An0cipated Results: MicroBooNE MicroBooNE sits in the wide- band, ~800 MeV, BNB beam at FNAL Over 3 years, 6.6e20 POT the 87 t ac0ve volume LAr TPC will see a large set of inclusive and exclusive interac0ons MicroBooNE 23

24 Summary LAr TPCs are a powerful method for studying neutrinos! The SBN program at FNAL Search for short base- line neutrino oscilla0ons Support LAr TPC detector R&D DUNE will follow and measure the neutrino mass hierarchy and possibly CPV Exci0ng results can be expected very soon from MicroBooNE with the beam returning soon! 24

25 Thanks! 25