Detector R&D for European projects Liquid Scintillator: LENA ICFA Neutrino European Meeting Paris, January 8 – 10, 2014 Wladyslaw H. Trzaska

Outline Why LSc? LENA concept and design – The 4 th generation of large LSc – Physics scope of LENA LENA as a far detector for beam experiments – CN2PY (very long baseline) – Neutrinos from ESS – DAEδALUS approach Conclusions ICFA, 9 January 2014W.H.Trzaska2

Why Liquid Scintillator? The lowest energy threshold High cross section & BGD-free IBD ~50 time more light than water Cherenkov – Performance / total cost ratio Robust construction Low running costs ICFA, 9 January 2014W.H.Trzaska3 Cinderella of neutrino detectors

sin 2 2θ 13 with LSc ICFA, 9 January 2014W.H.Trzaska4 Daya Bay should improve sin 2 2θ 13 precision from 14%  4% in 3-5 years!

20 kton 60 km from ~36 GW (thermal) MH (4σ in 6 years if Δm 2 xx ≈ 1%)* Precision measurement of mixing parameters – Δm %  0.6% – Δm %  0.6% – sin 2 θ 12 5%  0.7% SN Geo-neutrinos Sterile neutrinos ICFA, 9 January 2014W.H.Trzaska5 * From Yifang Wang: “no contradiction with F. Capozzi et al. arXiv: v1”

Key requirements for LENA To fulfill the scientific program (White Paper) – Very broad research scope: astroparticle physics, proton decay, geo-neutrinos, LBNO (MH & CPV) To reach/cross the discovery threshold Or at least to make a significant improvement over the ongoing large (~1 kton) LSc experiments – BOREXINO, KamLAND, SNO+, JUNO (20 kton) ICFA, 9 January 2014W.H.Trzaska6

 Design baseline ICFA, 9 January 2014W.H.Trzaska7 Size ~50 kton x 10 years = 0.5 Mton years – Approaching size limit for a single tank LSc detector? Transparency issues Cavern size and shape optimization ~4000 m.w.e. overburden  site selection – Cavern size limit at that depth? BOREXINO-grade radio-purity (Solar neutrinos) Low reactor anti-neutrino background (geo-neutrinos)

Expected rates in 50 kton LSc ICFA, 9 January 2014W.H.Trzaska8 L.Oberauer Neutrino 2012

LENA Design Studies Pre-feasibility Study TUM (till 26/05/2008) Feasibility Study TUM (till 12/04/2010) LAGUNA Design Study EU (2008 – 2011) LAGUNA–LBNO Design Study EU (2011 – 2014+) JUNO (2014 – 2024+) ICFA, 9 January 2014W.H.Trzaska9 + experience (since 1988) including BOREXINO and Double Chooz  Evolution of the Classic Design of LENA

ICFA, 9 January 2014W.H.Trzaska

ICFA, 9 January 2014W.H.Trzaska

ICFA, 9 January 2014W.H.Trzaska

Cost breakdown & potentially retrievable items ICFA, 9 January 2014W.H.Trzaska13

hydro-pumped-storage in Pyhäsalmi mine? Opportunity to continue M&O of the key infrastructure after the mine closure around 2019 Possible partial recuperation of the excavation costs after full completion of the scientific program ICFA, 9 January 2014W.H.Trzaska14

LENA’s potential for in-beam experiments CN2PY beam (very long baseline) – Full scientific program already without the beam – Independent (complementary) MH determination with CN2PY Neutrinos from ESS – LENA alone would not be sufficient for a significant measurement even if the detector would be located in Sweden (Garpenberg mine) DAEdALUS approach – Alternative option for CPV ICFA, 9 January 2014W.H.Trzaska15

LENA + CN2PY 2300 km ICFA, 9 January 2014W.H.Trzaska16

Neutrino flavor sensitivity of large LSc detectors LSc have been long known for their excellent calorimetric and timing properties (light yield, energy resolution) Advancements in signal processing and electronics allow now for flavor detection with the aid of e.g. pulse shape analysis, detection of Michel electrons, and rudimentary topology reconstruction Our simulations confirm that LENA should be able to discriminate with adequate efficiency between electron and muon neutrino induced events in the GeV range and yield MH with CN2PY beam ICFA, 9 January 2014W.H.Trzaska17

MH sensitivity with CN2PY ICFA, 9 January 2014W.H.Trzaska18

Illustration: muon track in Borexino ICFA, 9 January 2014W.H.Trzaska19 From: Tobias Stempfle

ICFA, 9 January 2014W.H.Trzaska20 Kai Loo at TAUP 2013

LENA as a CN2PY detector? LENA ready to be build already now (JUNO) LENA has a broad scientific program even without the beam LENA has sufficient flavor sensitivity to provide independent/complementary/reliable determination of MH with the CN2PY beam ICFA, 9 January 2014W.H.Trzaska21

DAEδALUS approach There is an alternative path towards CPV studies: ICFA, 9 January 2014W.H.Trzaska22

ICFA, 9 January 2014W.H.Trzaska23 Matt Toups TAUP2013

ICFA, 9 January 2014W.H.Trzaska24

ICFA, 9 January 2014W.H.Trzaska25 Summing up the merits of LENA Design & detector technology – Robust & mature – Refined by 4 consecutive Design Studies – Ready to implement now (JUNO) – Modestly priced & partially refundable Scintillator oil ~40% of total cost Cavern ~15% of total cost Physics potential – Top choice for astroparticle physics community – Excellent sensitivity to K+ channel for proton decay – MH determination with CN2PY beam Plan B to MH in Europe? – Wide CPV coverage (using D AE δ ALUS scheme) Plan B to CPV in Europe?

Thank you for your attention! Any questions? ICFA, 9 January 2014W.H.Trzaska26

LENA collaboration ICFA, 9 January 2014W.H.Trzaska27

The deepest mine in Europe Very small footprint Double access mode: Shaft and decline No water problem Excellent rock quality Cool environment 1400 m Modern infrastructure The most efficient mine of this type Excellent safety record Mining ends when science should begin (~2018) Lowest seismic activity Lowest reactor neutrino background Pyhäsalmi mine

PROTON DECAY LENA in the search for ICFA, 9 January 2014W.H.Trzaska29

Proton decay searches in large detectors ICFA, 9 January 2014W.H.Trzaska30 p   0 + e + favored by standard GUTs predicted proton lifetime:  ~ ? yrs current best limit from SK:  ≥ 5.4  yrs Large detection efficiency in water, and in this case, size does matter... p → K + + favored by SUSY, large BR in SUGRA predicted proton lifetime:  ≤ yrs current best limit from SK:  ≥ 2.3  yrs Low efficiency in water as the kaon is below Cherenkov threshold.  Window for „small“ detectors Courtesy: M. Wurm

ICFA, 9 January 2014W.H.Trzaska31 Signature of the K + decay _ Courtesy: M. Wurm

SUSY-favored decay mode Signaturep → K +     /      kaon visible in liquid scintillator!  fast coincidence signature (  K = 13 ns)  signal efficiency: ~65% (atm. bg)  remaining background: <0.1 ev/yr Signal detected in LSc detector ICFA, 9 January 2014W.H.Trzaska32 _ K+K+ ++ Limit for LENA if no event is observed in 10yrs (0.5 Mt. yrs):  p > 4x10 34 yrs (90%C.L.) Courtesy: M. Wurm

LENA Whitepaper ICFA, 9 January 2014W.H.Trzaska33

Key elements of LENA design Inner scintillator volume (~50kton) Non-scintillating volume in front of PMTs – Nylon sleeve/balloon (Borexino) – Large Optical Modules (LENA) – Acrylic inner sphere (JUNO) Muon Veto – Around the inner volume (already build-in) – Top layer above concrete (desirable) – Tracking layers (possible upgrade) Outer water tank – Passive shielding + WCh veto ICFA, 9 January 2014W.H.Trzaska34

Current choice for LENA: R ” PMT ICFA, 9 January 2014W.H.Trzaska35 In addition to Hamamatsu, ADIT Electron Tubes from UK/USA, and a Chinese manufacturer involved in JUNO experiment are expected to enter the competition. Needed: 34,000 PMTs Current cost: 1.4 k€ / PMT

Latest developments I: APD-based PMT ICFA, 9 January 2014W.H.Trzaska36 Courtesy: Hyper-K

Latest development II: MCP-based PMT ICFA, 9 January 2014W.H.Trzaska37 SBA photocatode New type of PMT: MCP-PMT Courtesy: JUNO

Optical Module Prototype ICFA, 9 January 2014W.H.Trzaska38 Current cost estimate(12” Hamamatsu): ~1400€ PMT + 500€ encapsulation/PMT

All electronics & computers will be located in auxiliary cavern ICFA, 9 January 2014W.H.Trzaska39

ICFA, 9 January 2014W.H.Trzaska40 Deck configuration

ICFA, 9 January 2014W.H.Trzaska41 LABAttenuation Length (430 nm) RAW14.2 m Vacuum distillation19.5 m SiO 2 column18.6 m Al 2 O 3 column22.3 m Courtesy: Daya Bay II Importance of LAB purification! Summary of the measured parameters Appendix in D3.1

ICFA, 9 January 2014W.H.Trzaska42

In 2012 new cavern outline proposed: 2 x 50 kton LAr + 1 x 50 kton LSc tank ICFA, 9 January 2014W.H.Trzaska43

ICFA, 9 January 2014W.H.Trzaska44