1

Sterile neutrinos in Icarus and Borexino

Paola Sala (Icarus)

Gioacchino Ranucci (Borexino)

INFN Milano

Milano 4-4- 2013

Outline

Neutrino oscillations and hints of sterile neutrinos.

The ICARUS-NESSIE Proposal at the CERN-SPS short baseline neutrino facility

Short Distance Neutrino Oscillations with BoreXino - SOX

Milano 4-4- 2013 Slide# : 2

The new physics frontier

The discovery of a Higgs boson at CERN/LHC has crowned the success of the Standard Model (SM).

Neutrino masses and oscillations represent today a main experimental evidence of a potentially unknown physics beyond the Standard Model.

Being the only elementary fermions whose basic properties are still largely unknown, neutrinos must naturally be one of the main priorities to complete our knowledge of the SM.

Milano 4-4- 2013 Slide# : 3

A candidate event in the

search for the Higgs

boson, showing two

electrons and two muons

(Image: CMS/CERN)

The first CNGS neutrino event in ICARUS

Milano 4-4- 2013 Slide# : 4

Neutrinos: a golden field for astro-particle physics

Neutrinos have been the origin of an impressive number of “Surprises”:

Masses, once zero “by ignorance”, are actually important

Oscillations extend and complete the C+KM quark mixing

Oscillations due to matter exist

But this is not all ! Important discoveries may be ahead:

CP violation in the lepton sector

Majorana or Dirac ’s; -less -decay,

-masses

Sterile neutrino and other “surprises”

Right handed neutrinos and see-saw mechanisms

The cosmological importance of neutrinos is immense

Neutrino flavors and oscillations

So far, 3 neutrino flavors

Combination of 3 mass eigenstates

3 mixing angles

2 mass differences

1 CP phase

neutrino Oscillations

In 2 flavors approximation:

INFN-CTS_march 2013 Slide# : 5

e

P () = sin2(2) sin2(1.27Dm2 L (m) /E (MeV) )

<-> e <->

Known oscillation parameters

Solar and reactor e, e disappearance : Davis, KamLand, SNO, Borexino…

Dm212= Dm2

solar =O (MeV) /O (100 km) ≈ 8 x 10-5 eV2

sin212 ≈0.3

Atmospheric and accelerator disappearance, : SuperKamiokande, Minos, Opera and Icarus @ CNGS, T2K

Dm223= Dm2

atm =O (GeV) /O (1000 km) ≈ 2.4 x 10-3 eV2

sin223 ≈ 0.39

Accelerator e , reactor e disapp. : DayaBay, Reno, T2K

sin223 ≈0.024

Mass Hierarchy and mass values are unknown

CP is unknown

From Z0 width : only 3 active neutrinos

However:

Milano 4-4- 2013 Slide# : 6

Some unexplained ->e events: The LNSD Anomaly

Milano 4-4- 2013 Slide# : 7

L/E ≈1

INFN-CTS_march 2013 Slide: 8

The MiniBooNE experiment at FNAL (1998-today)

L/E ≈1

Primary beam : 8 GeV/c protons

Neutino beam ≈ 1 GeV or .

Distance ≈ 500 m An event excess of 78.4±28.5 events

(2.8σ) is observed for anti-.

Low energy excess of 162.0±47.8 events (3.4σ) in neutrino mode

LSND-like exclusion from the present ICARUS experiment

Slide# : 9

● the present ICARUS limit ● the limits of KARMEN ● the positive signals of LSND and MiniBooNE

ICARUS result strongly limits the window of parameters for a possible LSND anomaly to a very narrow region (Dm2 ≈ 0.5 eV2 and sin22 ≈ 0.005) where there is an overall agreement (90% CL) of

limit of KARMEN

allowed MiniBooNE

allowed LSND 90% allowed LSND 99%

Eur. Phys. J. C 73 (2013)

present ICARUS

exclusion area

Milano 4-4- 2013

Milano 4-4- 2013 Slide# : 10

The Gallium and reactor disappearance anomaly

Recent re-evaluation of reactor antineutrino spectra The ratio R between the observed and predicted rates of previous experiments is decreased to R = 0.927 ± 0.023 , 3.0 from unity.

SAGE and GALLEX experiments recorded the calibration signal produced by intense artificial k-capture sources of 51Cr and 37Ar. The ratio R between the detected and predicted neutrino rates are consistent : R = (0.86 ± 0.05), about 2.7 from R=1

Can be fitted with neutrino oscillations around Dm2

new ≈ 2 eV2 and sin2(2new) ≈ 0.3.

Over-all evidence is mounting….

Milano 4-4- 2013 Slide# : 11

Combined evidence for some possible anomaly at ≈ 1 eV2: Could be the hint for the existence of one – or more- additional

neutrino?

Planck ?

What are “sterile” neutrinos ?

Sterile neutrinos are a hypothetical type of neutrinos that do not interact via any of the fundamental interactions of the Standard Model except gravity.

The name was coined in 1957 by Bruno Pontecorvo.

If they are heavy enough, they may also contribute to cold dark matter or warm dark matter.

Milano 4-4- 2013

Slide# : 12

Bruno Pontecorvo

Sterile neutrinos may mix with ordinary neutrinos

Oscillations into sterile neutrinos are detected as disappearance of ordinary neutrinos (reactors, Gallex anomalies)

Oscillations sterile detected as appearance (LSND)

A search for sterile neutrino :ICARUS-NESSIE at CERN

A new neutrino beam for a short base-line (L/E≈1) experiment

The experimental set-up will include a FAR and a NEAR detectors, identical except for dimensions

In absence of oscillations, apart some beam related small spatial corrections, the two spectra at different distances should a precise copy of each other,

The ICARUS Liquid Argon Time Projection chamber technology will allow for high precision, low background oscillation study

Magnetic spectrometers (NESSIE collab.) will be installed in far and near position for μ disappearance searches

This will presumably permit a definitive clarification of the “LNSD anomaly” in all the available oscillation channels in the same experiment.

ICARUS-NESSIE proposal, SPSC-P-347 , arXiv:1208.0862

Slide# : 13

New CERN SPS 2 GeV neutrino facility in North Area

100 GeV primary proton beam fast extracted from CERN-SPS in North Area: C-target station + two magnetic horns, ~110 m decay pipe, beam dump followed by stations. Interchangeable and focussing.

Near position (460 m) 150t LAr-TPC detector to be build anew + magnetic spectrometer

Far position (1600 m) ICARUS-T600 detector + magnetic spectrometer

Slide# : 14

Neutrino Telescopes, 11-15 March 2013 15

CNGS charge current interaction, one of TPC’s shown

Collection (top view)

Induction 2 (top view)

Induction 1 (frontal view)

2D projection for each of 3 wire planes per TPC 3D spatial reconstruction from stereoscopic 2D projections charge measurement from Collection plane signals

ICARUS LAr-TPC detection technique

Neutrino Telescopes, 11-15 March 2013 16

Two identical T300 modules (2 TPC chambers per module)

LAr active mass 476 t:

(17.9 x 3.1 x 1.5 for each TPC) m3; drift length = 1.5 m; Edrift = 0.5 kV/cm; vdrift = 1.6 mm/ms

3 readout wire planes at 0°, ±60°, 3mm plane spacing (for each TPC chamber):

53000 wires, 3 mm pitch 2 Induction planes, 1 Collection

PMT for scintillation light (128 nm): (20+54) PMTs trigger and t0

Hall B LN2 vessels

readout electronics

T300 T300

cryogenics (behind)

T300 module: two TPCs with the common cathode

cathode

readout wire arrays

E E

1.5m

Total energy reconstruction of events from charge integration. Full sampling, homogeneous calorimeter; excellent accuracy for contained

events.

ICARUS @ LNGS: the first LARGE LAr-TPC

INFN-CTS_march 2013 Slide: 17

T600 in hall B (CNGS2-2009)

The ICARUS Collaboration

1. INFN, LNGS, Assergi (AQ), Italy 2. Dipartimento di Fisica, Università di Genova, Genova, Italy 3. INFN, Sezione di Genova, 16146 Genova, Italy 4. Dipartimento di Fisica, Università di Padova, Padova, Italy 5. INFN, Sezione di Padova, 35131 Padova, Italy 6. INFN, LNF, 00044 Frascati (Roma), Italy 7. Dipartimento di Fisica Nucleare e Teorica, Università di Pavia, 27100 Pavia, Italy 8. INFN, Sezione di Pavia, 27100 Pavia, Italy 9. INFN, Sezione di Milano Bicocca, Dipartimento di Fisica G. Occhialini, 20126 Milano, Italy 10. INFN, Sezione di Milano e Politecnico, 20133 Milano, Italy 11. The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Science, Kraków, Poland 12. Department of Physics and Astronomy, University of California, Los Angeles, USA 13. Dipartimento di Scienze Fisiche, Università Federico II, 80126 Napoli, Italy 14. INFN, Sezione di Napoli, 80126 Napoli, Italy 16. INR-RAS, Moscow, Russia 17. CERN, Geneva, Switzerland 18. Los Alamos National Laboratory, New Mexico, USA 19. Institute of Physics, University of Silesia, Katowice, Poland 20. National Center for Nuclear Research, Warszawa, Poland 21. Institute for Radioelectronics, Warsaw University of Technology, Warsaw, Poland 22. INFN, Sezione di Catania, 95123 Catania, Italy 23. Dipartimento di Fisica e Astronomia, Università di Catania, 95123 Catania, Italy

M. Antonello1, B. Baibussinov5, V. Bellini22,23, H. Bilokon6, F. Boffelli8, M. Bonesini9, E. Calligarich8, N. Canci1, S. Centro4,5, A. Cesana10, K. Cieslik11, D. B. Cline12, A. G. Cocco14, D. Dequal4,5, A. Dermenev16, R. Dolfini7,8, C. Farnese4, A. Fava5, A. Ferrari17, G. Fiorillo13,14, G. T.

Garvey18, F. Gatti2,3, D. Gibin4,5, S. Gninenko16, F. Guber16, A. Guglielmi5, M. Haranczyk11, J. Holeczek19, A. Ivashkin16, M. Kirsanov16, J. Kisiel19, I. Kochanek19, A. Kurepin16, J. Łagoda20, G. Lucchini9, W. C. Louis18, F. Mammoliti22,23, S. Mania19, G. Mannocchi6, S. Marchini5, V.

Matveev16, A. Menegolli7,8, G. Meng5, G. B. Mills18, C. Montanari8, M. Nicoletto5, F. Noto22,23, S. Otwinowski12, T. J. Palczewski20, G. Passardi17, A. Pepato5, F. Perfetto13,14, P. Picchi6, F. Pietropaolo5, P. Płonski21, R. Potenza22,23

, A. Rappoldi8, G. L. Raselli8, M. Rossella8, C. Rubbia1,17, P. Sala10, A. Scaramelli10, E. Segreto1, D. Stefan1, J. Stepaniak20, R. Sulej20, C.M. Sutera22, O. Suvorova16, M. Terrani10, D. Tlisov16, R. G. Van de Water18, G. Trinchero6, M. Turcato5, F. Varanini4, S. Ventura5, C. Vignoli1, H. G. Wang12, X. Yang12, A. Zani8, K.

Zaremba21.

CNGS : mainly , E≈20 GeV

L =732 km

Shut down dec.3 2012

Icarus since 2010:

detector live-time > 93%

Superluminal searches (P. L. B711 (2012) 270, P. L. B713 (2012), JHEP

11 (2012) 049)

e ”LSND/MiniBooNE” anomaly (Eur. Phys. J. C (2013))

Milano 4-Apr-2013 Slide# : 19

ICARUS in the CNGS beam

p

K

μ

Precise particle tracking and identification

Collection

cathode

CNGS

beam primary vertex

kaon

Induction

3D reconstruction dE/dx based PID

New 2D => 3D approach for LAr TPC (in press: AHEP, arXiv:1210.5089)

3D object driven by optimization of its 2D projections

(no need for drift matching)

Milano 04-04-2013 Slide# : 20

Run 9927 Event 572: -CC CNGS event

Track

1 ()

2

3 (p)

Sec. vtx.

4

5 ()

6 (K)

7

8

Edep[MeV]

2701.97

520.82

514.04

797

76.99

313.9

86.98

35.87

283.28

cosx

0.069

0.054

-0.001

0.009

0.000

0.414

-0.613

cosy

-0.040

-0.420

0.137

-0.649

-0.239

0.793

0.150

cosz

-0.997

-0.906

-0.991

0.761

-0.971

-0.446

-0.776

Collection

Induction2

0

Conversion distances 6.9 cm, 2.3 cm

Primary vertex (A):

very long (1), e.m.cascades(2), (3)

Secondary vertex (B):

the longest track (5) is a coming from stopping k (6). decay is observed

Total visible energy 4.5 GeV

close-up of two e.m. showers

A B

3D

θ

Eg = 685 ± 25 MeV

Eg = 102 ± 10 MeV

Collection

mπo = 127 ± 19 MeV/c²

θ = 28.0 ± 2.5º

pπo = 912 ± 26 MeV/c

e/g separation: dE/dx in cascade initial part

INFN-CTS_march 2013 Slide# : 22 Venice_March2013

• MC: single electrons (Compton) • MC: e+ e– pairs (g conversions) • data: EM cascades (from 0 decays)

• ~0.02 X0 sampling; g’s separated from vtx; • g rejection increases with energy; • e selection efficiency const with energy;

1 m.i.p.

2 m.i.p. 1 m.i.p.

2 m.i.p.

MC

o reconstruction:

A new result : LNSD search at CNGS

CNGS facility delivers an almost pure beam at 730 km peaked in the range 10 ≤ E ≤ 30 GeV (beam associated e about 1/2%) looking visually for the signature of a e signal.

Main differences with respect to the LNSD experiment are:

L/E ~ 1 m/MeV at LNSD, but L/E≈36.5 m/MeV at ICARUS

E oscillation signal averages to sin2(1.27Dm2new L /E) ~1/2 and

<P>→e ~ ½ sin2(2new)

INFN-CTS_march 2013 Slide# : 23

An initial electron progressively transforming into a shower in Lar-TPC

The ICARUS T600 as “Far” detector

Slide: 24

●T600 will be transported to CERN in 2013, after decommissioning at LNGS, ensuring the new experiment operation again in 2016

●A large number of components will be disassembled and transported: inner detectors, electronics, ancillary systems, LN2 liquefaction system

●TPC’s will be inserted in new vessels and new external insulation

Slide# : 24 INFN-CTS_march 2013

Near detector : T150

(1/4 T600):

Expected signals for LSND/MiniBooNE anomalies

Event rates in the near (330 m) and far (1600 m) LAr detectors for 4.5 1019 pot.

Oscillated signals clustered below 6 GeV of visible energy.

negative focusing positive focusing

NEAR FAR NEAR FAR

+ anti- (LAr) 2030 K 270 K 5250 K 670 K

e + anti-e (LAr) 35 K 4.2K 54 K 6.4 K

sin2(2)=0.96, Dm2=0.064 eV2 421 1420 1360 4420

sin2(2)=0.02, Dm2=0.4 eV2 591 360 1900 914

sin2(2)=0.002, Dm2=2 eV2 332 784 1080 2420

sin2(2)=0.0066, Dm2=4.42 eV2 5670 989 17 K 2400 Slide# : 25

All beam-line parameters still under optimization (including the new near position at 460 m)

A possible expectation of LSND mass and mixing angle

Slide# : 26

● Events rates shown both for [background] and [oscill.+background] at d=330 m and d=1600 m and the optimal “predictions” from ICARUS et al. Dm2 = 0.4 eV2, sin2(2) = 0.01

● For d=1.6 km, E < 5 GeV and 4.5 1019 pot (1 y) a e oscillation signal of ≈1200 events is expected above 5000 backgr. events

T150 near detector T600 far detector

INFN-CTS_march 2013

Exploring all channels: expected sensitivity e-appearance: 1 year μ beam (left) 2 year antiμ beam (right) for 4.5 1019 pot/year, 3% syst. uncertainty on energy spectrum.

μe μe

e/-disappearance: 1 year μ ee

combined “anomalies”: from reactor s, Gallex and Sage experiments.

LSND allowed region is fully explored in both cases

Slide# : 27 INFN-CTS_march 2013

Time Schedule (ICARUS)

Slide 28

INFN-CTS_march 2013

3 years

INFN-CTS_march 2013 LNGS_May2011 Slide 29

Thank you !

Recent Planck 2013 results from Big Bang cosmology

A cosmologic search for additional neutrino-like relativistic particles beyond the three families of neutrinos in the standard model has been reported by the Planck collaboration.

INFN-CTS_march 2013 Slide# : 30

We conclude that the tension between direct H0 measurements and the CMB and BAO data in the base Λ CDM can be relieved at the cost of additional neutrino-like physics

This demonstrates the extreme complexity of the situation

Neff = 3.36 ±-0.64   

+0.68 (95%; Planck+WP+highL)

Neff = 3.30 ±-0.51  

+0.54 (95%; Planck+WP+highL+BAO)

Neff = 3.52 ±-0.45  

+0.48 (95%; Planck+WP+highL+H0+BAO)

N=3 N=4