Exploring the Invisible Universe Ke Han September 6, 2017 from Deep Underground Shanghai Jiao Tong University

09/05/17 Ke Han (SJTU) 1 Dark Matter and neutrino physics

• Physics beyond the Standard Model. • Interconnects particle physics, nuclear physics, cosmology, and astrophysics.

European ITN project US HEP

09/05/17 Ke Han (SJTU) 2 Dark Matter and neutrino physics at SJTU

• PandaX • Dark Matter (WIMP) direct detection with Xenon TPC • JUNO and Daya Bay • Neutrino oscillation physics • PandaX-III and CUORE • Neutrinoless double beta decay

Members: • 7 faculty; 6 engineers; 6 postdocs; 14 students

Xiangdong Ji Jianglai Liu Karl Giboni Changbo Fu Ke Han Yong Yang Ning Zhou

09/05/17 Ke Han (SJTU) 3 Dark Matter

• Existence of dark matter is firmly established • Particle nature of dark matter? • WIMP?

09/05/17 Ke Han (SJTU) 4

WIMP searches

Slatyer Tracy Tracy

09/05/17 Ke Han (SJTU) 5 “Dark matter rush” around the world

CJPL Y2L Kamioka SURF PandaX COSINE XMass LUX CDEX

LNGS Modane XENON1T Canfranc EDELWEISS DarkSide Soudan SNOLAB ANAIS MIMAC DAMA CDMS DEAP/CLEAN

09/05/17 Ke Han (SJTU) 6 CJPL – Deepest underground physics lab in the world

Science Mag.

CJPL-I

From Yue Qian CJPL-I

CDEX PandaX

09/05/17 Ke Han (SJTU) 7 PandaX hall at CJPL-II

Experiments at CJPL-II • PandaX projects • CDEX • JUNA (accelerator) • Jinping neutrino experiment (LS) • …

Storage Crane Crane Rn free Purge Offices platform rail clean room room PandaX at Hall B2 • Extra excavation for the water shielding pool (finished) • Shared facility of DM and 0νββ searches • Beneficial occupancy by the beginning of 2018

Class 10000 clean room Semi clean area

09/05/17 Ke Han (SJTU) 8 PandaX Projects

Dark matter WIMP searches

PandaX-I: 120kg LXe PandaX-II: 500kg LXe PandaX-xT LXe (2009 – 2014) (2014 – 2018) (Future)

0νββ searches

PandaX-III: 200kg - 1 ton HPXe (Future)

09/05/17 Ke Han (SJTU) 9 PandaX collaboration

Shanghai Jiao Tong Central China Normal University University Peking University Yalong Hydropower Shandong University Company Shanghai Institute of Applied University of Maryland, USA Physics Lawrence Berkeley National University of Science and Lab, USA Technology of China CEA Saclay, France China Institute of Atomic University of Zaragoza, Spain Energy Suranaree University of Sun Yat-Sen University Technology, Thailand

09/05/17 Ke Han (SJTU) 10 Dual phrase Xe TPC for dark matter

09/05/17 Ke Han (SJTU) 11 Best limit achieved

Details at Xiangyi’s talk

09/05/17 Ke Han (SJTU) 12 PandaX-xT

• Preparing new experiments in CJPL-II, hall #B2 • Intermediate stage: • PandaX-4T (4-ton target) with SI sensitivity ~10-47 cm2 • On-site assembly and commissioning: 2019- 2020 • Eventual goal: G3 xenon dark matter detector (~30T) in CJPL to “neutrino floor” sensitivity

09/05/17 Ke Han (SJTU) 13 Neutrinos: what do we know

• We know three generations of neutrinos: • Electron • Muon • Tau • Neutral • Weakly interacting

• Neutrino Flavor transitions and mixing of massive neutrinos • Two hierarchical mass scales 2 Δm . e- p • Three mixing angles W- n

09/05/17 Ke Han (SJTU) 14 What are some open questions?

2 • Mass hierarchy: the sign of Δm23 • Mid-baseline reactor antineutrino experiment • The nature of the massive neutrinos – Dirac or Majorana? • Double beta decay experiment • The absolute mass scale • Beta decay end-point measurement • CP violating phase δ. • Long baseline accelerator neutrino experiment • The existence of sterile neutrinos • Short baseline reactor antineutrino experiment • Source experiments

neutrinos d sb u c t e m t

m e k M G T

e

V

e

e

e e

V

V

V

V V

09/05/17 Ke Han (SJTU) 15 Daya Bay and JUNO

Previous site candidate

Guang Zhou

2.5 h drive Lufeng Shen Zhen Huizhou NPP NPP Daya Bay Zhu Hai NPP Hong Kong

Macau 53 km 53 km Taishan NPP Yangjiang NPP

09/05/17 Ke Han (SJTU) 16 Reactor Antineutrino Anomaly: 235U or sterile neutrino?

Daya Bay, Chin. Phys. C 41(1) (2017) • Daya Bay observed a flux deficit in comparison to the model calculation flux. • Hint of sterile neutrino?

• More recently, observed correlations between reactor core fuel evolution and changes in the reactor antineutrino flux and energy spectrum • 235U flux calculation problem or Sterile neutrino?

09/05/17 Ke Han (SJTU) 17 Neutron Calibration Campaign

r =1.775m r =0m r =1.35m • At Daya Bay, inverse beta decay (IBD) to detect antineutrinos + 휈푒ҧ + 푝 → 푒 + 푛 Liquid Scint. (LS)

• Dominant systematic uncertainty for Gd LS antineutrino detection is the efficiency for IBD neutron

• Extensive neutron calibration campaign at the end of 2016 • AmC and AmBe (few MeV) sources along n-H capture n-Gd three z-axes of the automated calibration (2.2MeV) (≈8MeV) units (ACU) • Target: improve the IBD detection efficiency (x2)  more precise reactor flux measurement

09/05/17 Ke Han (SJTU) 18 MH determination with reactor neutrinos

• Determine MH with reactors: oscillation

probability independent of CP phase and θ23 .

09/05/17 Ke Han (SJTU) 19 JUNO: Jiangmen Underground Neutrino Observatory

• Central Detector: Top • Acrylic sphere (Φ=35.4m) + Calibration tracker • Stainless steel latticed shell (Φ=40.1m ). • Liquid scintillator: 20 kton • PMTs: • ~17,000 20” PMTs + ~25,000 3” PMTs • photocathode coverage >75%. • Water Cherenkov: Water pool • 35 kton pure water + 2,000 20” veto PMTs

Central detector

• With 6-years, determine MH at >3 (4) for JUNO-alone (JUNO + accelerator experiments) with the energy resolution < 3%/√퐄(퐌퐞퐕) 09/05/17 Ke Han (SJTU) 20 JUNO calibration system

• Goal: <3%/ 퐄(퐌퐞퐕) energy resolution, <1% energy scale uncertainty

Automatic Calibration Unit (ACU)

Two cable loop systems (CLS)

• ACU: Scan the central axis (1D) • CLS: Scan one vertical plane (2D) Remotely Operated • Vehicle (ROV) ROV: Scan “everywhere” (3D) Source storage • Guide Tube: Scan boundary

09/05/17 Ke Han (SJTU) 21 July 5, 2012 0:12 WSPC/ INSTRUCTION FILE bb0-hep

July 5, 2012 0:12 WSPC/ INSTRUCTION FILE bb0-hep

14

cases in which cancellations can happen are the following ones in which CP is conser ved: 14 2i α 12 2i α 13 e = − 1and e =+1. The value of m1 for which cancellations suppress |mββ | is slightly decreased bycatshees DinawyahicBhaycamnceeallasutrioenmsecnatnofhaϑp13pe,bn eacreautsheetfhoellowing ones in which CP is 2 larger valueof sin ϑ13m3 addcos tnoserthveedc:ontribution of m1. Hence, a smaller value of m is required to cancel the sum of the contributions of m and m with the 1 2i α 12 2i α 13 1 3 e = − 1and e =+1. The value of m1 for which cancellations suppress opposite contribution of m2. |mββ | is slightly decreased by the Daya Bay measurement of ϑ13,because the 2i α 12 2i α 13 e = − 1and e = − 1. The value of m1 for 2which cancellations suppress larger valueof sin ϑ13m3 adds to the contribution of m1. Hence, a smaller value |m | is slightly increased by the Daya Bay measurement of ϑ ,because the ββ of m1 is required to cancel the sum13of the contributions of m1 and m3 with the 2 Neutrinoless doublelarger va lubetae of sin ϑdecay13m3 adds toopthpeoscitoenctoribnturibtioutnioonf omf m2.2H. ence, a larger value 2i α 12 2i α 13 of m1 is required to cancel tehe co=ntr−ib1autniodne of m=1 −w1it. hThtehevaoluppeoosfitems1umfor owf hich cancellations suppress contributions of m2 and m3. |mββ | is slightly increased by the Daya Bay measurement of ϑ13,because the 2 larger value of sin ϑ13m3 adds to the contribution of m2. Hence, a larger value Figure 2 shows thate the two effects lead to a slight widening of the cancellation • Explores the Majorana nature of neutrinosof m1 is required to cancel tMajoranahe contribution oNeutrinof m1 with the opposite sum of band after the Daya Bay measurement of ϑ . • Tests lepton number conservation contribu13tions of m2 and m3. • ΔL = +2 Figure 2 shows thate the two effects lead to a slight widening of the cancellation 4.2. Inver ted hierarchy of thebanndeuatfrteirntohemDasaysaeBsay measurement of ϑ13. • 0νββ is not Ijustn this ac aneutrinose, for the n experiment!eutrino masses we have • Connects to broad neutrino oscillation4.2. physicsInver ted hi pictureerarchy of 2the neutr i no masses 2 2 2 ∆ ms 2 m3 ∆ ma ,m1 ∆ maI,mn this2case, f∆ormthae n1+eutrino m2asses we ∆hamvea. (60) 2∆ ma 2 2 2 2 2 ∆ ms 2 Example: In the expression of |mββ |, the contmrib3 ution∆omf at,mhe te1rm m∆3 msina ,mϑ13 2can b∆emsafely1+ 2 ∆ ma. (60) 2 2∆ ma neglected. Neglecting also the small contribution of sin ϑ13,from Eq. (48) we find 2 136 136 − In the expression of |mββ |, the contribution of the term m3 sin ϑ13 can be safely 푋푒 → 퐵푎 + 2푒 + 2휈ഥ 2 2 2 2 푒 |mββ | ∆nmegalec1te−d. sNinegle2cϑt12ingsinalsoαt12he.small contribution o(6f 1sin) ϑ13,from Eq. (48) we find

2 2 2 The phase α12 is the only unknown parameter in th|meβeβx|press∆iomn afo1r −thseinef2feϑc12tivsine α12 . (61) Majorana mass in the case of a inverted mass hierarchy. The phase α is the only unknown parameter in the expression for the effective From Eq. (61) we find the following range12for |m |: Majorana mass in theββcase of a inverted mass hierarchy.

Fro2m Eq. (61) we find t2he following range for |mββ |: cos2ϑ12 ∆ ma ≤ |mββ | ≤ ∆ ma. (62) 2 2 The upper and lower bounds of this inequality ccoorsr2esϑp12ond∆ mtoa ≤th|emβcβa|s≤eof∆ ma. (62) CP-invariance in the lepton seTcthoer. uIpnpefracatn,dCPloweinr vbaoruianndcse oimf tphlieissintehqautalit(syeecorrespond to the caseof Refs.50,33,59) CP-invariance in the lepton sector. In fact, CP invariance implies that (see Refs.50,33,59) 2i α 12 ∗ e = η2 η1 , (63) 2i α 12 ∗ e = η2 η1 , (63) where ηk = ± i is the CP parity of the Majorana neutrino νk .If η2 = η1,we where ηk = ± i is the CP parity of the Majorana neutrino νk .If η2 = η1,we have α12 =0, π (the upper bound in the inequality (62)). If η2 = − η1 we have have α12 =0, π (the upper bound in the inequality (62)). If η2 = − η1 we have α12 = ± π/ 2 (the lower bound in the inequality (62)). α12 = ± π/ 2 (the lower bound in the inequality (62)). 09/05/17 Ke Han (SJTU) 22 e We are very grateful to Michele FrigeerWeio faorre pveoriyntginragteofult tao mMicsthaekleeFirnigtehrieo cfoarncpeolilnattiinognobuat nadmist ake in the cancellation band presented in the first arXiv version of thiprsespaentpeedr ianndtheinfiristtsapurXblivisvheersdiovnerosfitohins(paMopd.er aPndhysin. Litestput. blAished version (Mod. Phys. Lett. A 27 (2012) 1230015). 27 (2012) 1230015). Neutrinoless double beta decay

• Measure energies of emitted e- (universal approach) • Electron tracks are a huge plus (unique feature of certain experiments) • Daughter nuclei identification (ultimate

From Physics World dream?)

2νββ

0νββ

T-REX: arXiv:1512.07926

Sum of two electrons energy Simulated track of 0νββ in high pressure Xe

09/05/17 Ke Han (SJTU) 23 Major 0νββ experiments around the world

CJPL Y2L Kamioka SURF PandaX-III AMoRE KamLAND-Zen Majorana CANDLES

LNGS CUORE Canfranc Modane GERDA WIPP SNOLAB NEXT SuperNEMO COBRA EXO-200 SNO+

09/05/17 Ke Han (SJTU) 24 PandaX-III: high pressure gas TPC for 0νββ of 136Xe

• TPC: 200 kg scale, symmetric, double- ended charge readout, with 10 bar of 136Xe • Main features: good energy resolution and background suppression with tracking

09/05/17 Ke Han (SJTU) 25 PandaX-III TPC illustrated

High Pressure High Voltage Feedthrough Vessel • ~4m3 active volume

MicromegasCharge Readout Plane • 10 bar working pressure • ~10000 readout channels e • Xe+TMA gas mixture Mixture of enriched e 136Xe and 1% TMA e E • Charge-only readout with e e microbulk Micromegas Drift electrons

E Field E Field

Field Cage Cathode

09/05/17 Ke Han (SJTU) 26 Prototype TPC at SJTU

• 16 kg of xenon at 10 bar (active mass within TPC) • Single-ended TPC • Data taking with Ar, Xe, Xe+TMA at different pressures • Two Micromegas modules installed. Movable source used for calibration

55Fe

Shielded 241Am

09/05/17 Ke Han (SJTU) 27 CUORE (Cryogenic Underground Observatory for Rare Events)

• Search for 0νββ of 130Te and other rare events

• 988 TeO2 crystals run as a bolometer array • 741 kg total; 206 kg 130Te • 1027 130Te nuclei

09/05/17 Ke Han (SJTU) 28 CUORE (Cryogenic Underground Observatory for Rare Events)

• Search for 0νββ of 130Te and other rare events

• 988 TeO2 crystals run as a bolometer array • 741 kg total; 206 kg 130Te • 1027 130Te nuclei • 10 mK base temperature in a custom dilution refrigerator

09/05/17 Ke Han (SJTU) 29 CUORE (Cryogenic Underground Observatory for Rare Events)

• Search for 0νββ of 130Te and other rare events

• 988 TeO2 crystals run as a bolometer array • 741 kg total; 206 kg 130Te • 1027 130Te nuclei • 10 mK base temperature in a custom dilution refrigerator • Gran Sasso underground lab (LNGS), Italy • 3600 m water equivalent • Muon Flux at LNGS: ~3x10-8 μ/(s cm2)

09/05/17 Ke Han (SJTU) 30 2017: a great year for CUORE

• Data taking started early this year • First physics result in July Future • CUPID (CUORE with particle ID) • Enrichment • Phonon + photon dual readout • Multiple crystal choices • Active discussion of CUPID-China

09/05/17 Ke Han (SJTU) 31 Conclusions

• Very active mega-group on dark matter and neutrino physics • WIMP search • Neutrino oscillation • Neutrinoless double beta decay • PandaX, the Flagship experiment founded and led by SJTU, has been a huge success • World-leading results • In China: pioneering effort; broad impact • International collaboration in both directions

09/05/17 Ke Han (SJTU) 32