1. LNGS Scientific Committee – April 8,,2005 1G.Battistoni for the ICARUS Coll. ICARUS (CERN-CNGS2) A Second-Generation Proton Decay Experiment and Neutrino Observatory at the Gran Sasso Laboratory

2. LNGS Scientific Committee – April 8,,2005 2G.Battistoni for the ICARUS Coll. The ICARUS Collaboration 25 INSTITUTIONS, 150 PHYSICISTS CIEMAT Granada UCLA ETHZ INR IHEP Katowice Krakow Warsaw, Wroclaw L’Aquila, LNGS, Milano, Napoli, Padova, Pavia, Pisa, LNF

3. LNGS Scientific Committee – April 8,,2005 3G.Battistoni for the ICARUS Coll. The T600 modules are now at LNGS

4. LNGS Scientific Committee – April 8,,2005 4G.Battistoni for the ICARUS Coll. The milestones for T600 installation and operation at LNGS we are here

5. LNGS Scientific Committee – April 8,,2005 5G.Battistoni for the ICARUS Coll. We are on schedule On Monday 11 th April the Air Liquid work begins (T600 yard) T600 Mechanical frame construction completed

6. LNGS Scientific Committee – April 8,,2005 6G.Battistoni for the ICARUS Coll.

7. LNGS Scientific Committee – April 8,,2005 7G.Battistoni for the ICARUS Coll. ICARUS status o The ICARUS collaboration has built and run the T300 module on time and within budget o The T3000 design was approved o After that there were long delays not due to ICARUS responsibility o The project of the muon spectrometer has been indefinitely postponed by proponent groups o The two modules composing the T600 have been delivered to LNGS o INFN has provided essentially all the money for the T600, for the basic infrastructures and for the first T1200 module. o INFN correctly argues that the second T1200 module should be substantially funded by non italian collaborators. This is not yet the case. o At this time, a T1800 configuration (T600+T1200) running for a significant time interval has to be considered as a necessary firm (i.e. possible and financed) step in the ICARUS project towards the completion of the final mass design.

8. LNGS Scientific Committee – April 8,,2005 8G.Battistoni for the ICARUS Coll. T1200 o INFN has formally authorized the necessary calls for tender o However these steps are frozen waiting for the MoU document We need to have a green light as soon as possible

9. LNGS Scientific Committee – April 8,,2005 9G.Battistoni for the ICARUS Coll. The T1800 configuration

10. LNGS Scientific Committee – April 8,,2005 10G.Battistoni for the ICARUS Coll. Physics with T1800 o In view of the previous considerations, the physics goals achievable with the T1800 are being reviewed by the collaboration. o INFN also recommended this analysis, asking for an update of the previous documents on the physics goals, in the light of the recent progresses in the topics which are within the ICARUS interest.

11. LNGS Scientific Committee – April 8,,2005 11G.Battistoni for the ICARUS Coll. An update of The Physics Program with T1800 proton and neutron decay searches atmospheric neutrinos Long Baseline Neutrino Experiment solar neutrinos Cosmic neutrinos: SN,  -ray bursts, neutron star collapse uuduud ee dddd p 00

12. LNGS Scientific Committee – April 8,,2005 12G.Battistoni for the ICARUS Coll.

13. LNGS Scientific Committee – April 8,,2005 13G.Battistoni for the ICARUS Coll. Basic features of T1800 Instrumented volume of T600: 340.35 m 3  476.5 t LAr Instrumented volume of T1200: 710.51 m 3  994.5 t LAr Energy resolution:  /E = 11%/  E(MeV) E<50 MeV checked with  decay  /E = 3%/  E(GeV)  1% e.m. showers checked with   mass drift length: 3m drift length: 1.5m

14. LNGS Scientific Committee – April 8,,2005 14G.Battistoni for the ICARUS Coll. 1) Nucleon Decay This remains the original and most important physics item addressed by ICARUS The work exposed in the previous proposal documents remains valid full event simulation (FLUKA) with all relevant effects in Argon nuclei (including absorption or decay inside parent nucleus) background evaluated on a statistical sample of 100 kton yr exposure Topological and kinematical cuts as described in previous proposals essential ingredients:

15. LNGS Scientific Committee – April 8,,2005 15G.Battistoni for the ICARUS Coll.

16. LNGS Scientific Committee – April 8,,2005 16G.Battistoni for the ICARUS Coll. Comments on nucleon decay Despite the reduction in mass, T1800 has still the capability to improve the current limits for several channels even with an exposure of few years. In less than one year it is possible to improve SuperKamiokande limits on the following channels: p     n  e - K + In all cases where exclusive channels are considered, the background is found to be much below 1 ev/kton yr, thus allowing a discovery capability even with the observation of a single event

17. LNGS Scientific Committee – April 8,,2005 17G.Battistoni for the ICARUS Coll. 2) Atmospheric Neutrinos From the analysis of the Super-Kamiokande significative systematic uncertainties remain on the e sector, and in particular in the SubGeV region These appear in the comparison of absolute normalization between data and predictions (see Super-Kamiokande results)Super-Kamiokande results These SubGeV e events might be important for the progress of the understanding of neutrino oscillations ICARUS can study e events with an unprecedented level of experimental systematics in addition to a very low threshold in lepton momentum

18. LNGS Scientific Committee – April 8,,2005 18G.Battistoni for the ICARUS Coll. Why SubGeV e are important There is no evidence for atmospheric e oscillation: sin 2  13 is consistent with 0 in the present 3 flavor analysis (  m 2 23, sin 2  23, sin 2  13 ) After solar and KamLAND results, we can say that oscillation of low energy e should appear at some level even if sin 2  13 = 0 sub-leading oscillations driven by  m 2 12 F osc e = F 0 e P( e  e ) + F 0  P(   e ) F 0 e,F 0   flux w/o osc. = F 0 e [ P( e  e ) + r P(   e ) ] r = F 0   / F 0 e :  /e flux ratio = F 0 e [ 1 – P 2 + r cos 2  23 P 2 ] P 2 = |A e  | 2 : 2 transition probability e   in matter driven by  m 2 12 (F osc e / F 0 e ) – 1 = P 2 ( r cos 2  23 – 1) screening factor for low energy ( r ~ 2 ) ~ 0if cos 2  23 = 0.5 (sin 2  23 = 0.5) 0.5) > 0if cos 2  23 > 0.5 (sin 2  23 < 0.5)

19. LNGS Scientific Committee – April 8,,2005 19G.Battistoni for the ICARUS Coll. Consequences The knowledge of the absolute level of SubGeV e can provide the best possible measurement of  23 and of its octant. Of course, from the point of view of statistical significance, this requires a very high exposure This can be achieved in a next detector generation in the ICARUS programme, but the unique features of T1800 can provide a first important indication and comprehension of the experimental systematics of SubGeV e. T1800 can explore for the first time the region with P e <100 MeV/c

20. LNGS Scientific Committee – April 8,,2005 20G.Battistoni for the ICARUS Coll. New improved detector simulation a first study of containment using full simulation FLUKA + NUX with 3-f oscillations with matter effects (with F.Vissani, LNGS) Atmospheric neutrino Fluxes (2002). Baseline exposure: 1 yr 600 Tons + 4 yr 1800 Tons: 6.36 kton yr Choice of oscillation parameters (SK and solar exp. results)  m 2 23 = (1.5) - 2.1 – (3.4) x10 -3 eV 2 (positive)  m 2 12 = 8.3x10 -5 eV 2 sin 2 2  12 = 0.825 sin 2 2  23 = 1.  CP = 0 o   13 = Chooz limit 11 o merging with K2K:  m 2 23  = 2.5 x10 -3 eV 2 Generated Statistics: 20 times larger

21. LNGS Scientific Committee – April 8,,2005 21G.Battistoni for the ICARUS Coll. Event selection and definition Follow SK denomination but with different limits: Sub-GeV Evis < 1.0 GeV (SK: <1.33 GeV) Multi-GeV Evis > 1.0 GeV (SK: >1.33 GeV) Super-Kamiokande Icarus e (single prong) 100 MeV10 MeV muon (single prong)200 MeV10 MeV Multi.prong muon600 MeV10 MeV CC Interaction rates: evt/kton yr  m 23 2

22. LNGS Scientific Committee – April 8,,2005 22G.Battistoni for the ICARUS Coll. 1  statistical uncertainty level on e normalization achievable with T1800 for the baseline exposure { 15% excess level as seen by Super-Kamiokande Main results Possibility to separate charges (~75% probability capture for   ) With containment requirement 255 200 we can measure  - /  + with ~ 25% error or less T.Suzuki et al., Phys. Rev. C35 (1987) 2212

23. LNGS Scientific Committee – April 8,,2005 23G.Battistoni for the ICARUS Coll. We can use charge id by  -decay to test the nuclear model: important for many future neutrino experiments Our model prediction: in SubGeV  -like events (~all q.e.) there is a recoiling proton with E>50 MeV in: ~42% of  interactions ~14% of  interactions examples of “anomalies”:   p decay p  

24. LNGS Scientific Committee – April 8,,2005 24G.Battistoni for the ICARUS Coll. ICARUS T600+T1200 ν τ appearance To be combined with expected OPERA results Increase the overall sensitivity Δ m 2 = 2.5 x 10 -3 eV 2 5 years exposure of T600(5y) +T1200 (4y) Expected rate Nominal CNGS beam: 6.5 ν τ with 0.3 bg events CNGS x 1.5 beam intensity 9.8 ν τ with 0.5 bg events 3) Neutrino oscillations with the CNGS beam

25. LNGS Scientific Committee – April 8,,2005 25G.Battistoni for the ICARUS Coll. ICARUS T600+T1200 ν e appearance New beam simulations with latest optics 3 Flavour oscillations with matter effects Full simulation in LAr Fiducial volume 90% Cut on Evis < 20 GeV optimized for background reduction All backgrounds included ν τ CC τ →e 12.6 ev ν e + ν e intrinsic CC 47 ev Neutral currents suppressed by e / π 0 discrimination: 0.1% π 0 misidentification with 90% e efficiency

26. LNGS Scientific Committee – April 8,,2005 26G.Battistoni for the ICARUS Coll. ICARUS T600+T1200 ν e appearance Evis spectra Δ m 2 23 =2.5 10 -3 eV 2 Sin 2 (2 θ 13 )= 0.14 (CHOOZ limit) 25 oscillated events 90% confidence level Full = CNGS std. 1y t600 +4y t1800 Dashed = CNGS x 1.5 5% systematic error on background

27. LNGS Scientific Committee – April 8,,2005 27G.Battistoni for the ICARUS Coll. CNGS low energy 5 y CNGS low energy focalization, 400 GeV p on 1m long target 4.5 10 19 pot/y Average ν μ energy 1.8 GeV, 0.9% ν e / ν μ CC Evis <2.5 GeV Δ m 2 23 =2.5 10 -3 eV 2 Sin 2 (2 θ 13 )= 0.14 (CHOOZ limit) 13.5 oscillated events over 2.9 background events 90% CL sensitivity. Factor 4 over CHOOZ Full: CNGS Low-e Dashed: CNGS τ

28. LNGS Scientific Committee – April 8,,2005 28G.Battistoni for the ICARUS Coll. Muons from ν interactions in GS rock All details of μ transport included Expected: 43.6 μ /m 2 /10 19 pot  0.98 μ/m 2 /day  196 μ/m 2 /year In T600 : 3700 μ/year, of which 870 μ/year with P μ >20GeV ( mostly from ν μ with E ν >40GeV) Importance: a)beam monitoring b)measurement of the high energy sector of neutrino flux: they mostly come K which also contribute to e contamination

29. LNGS Scientific Committee – April 8,,2005 29G.Battistoni for the ICARUS Coll. 4) Solar neutrinos Solar neutrino event rates rescaled to T1800 volume. Fluxes taken from BP04 SSM ( 8 B flux larger by 14% with respect to BP2000)BP04 SSM Calculation of the absorption cross-section in the neutrino energy range 1.5 – 15 MeV from new measurements from 40 Ti  + decay A full simulation based on FLUKA package was performed, using a detailed description of the different layers and materials of the T600 detector, to study the topology and the rates of the solar neutrino and neutron capture background Detailed analysis of background neutron sources: a) External sources (natural radioactivity of the rocks): 2  10 6 capt/year b) Internal sources (Al, stainless steel, etc…): 3  10 6 (optimistic) capt/year 13  10 6 (pessimistic) capt/year

30. LNGS Scientific Committee – April 8,,2005 30G.Battistoni for the ICARUS Coll. We must increase the threshold of 5 MeV previously quoted in the original proposal due to the Q-value of the neutron capture processes on 36 Ar, no background is expected above 9 MeV. ICARUS T1800 can therefore provide accurate information on the high energy region of the solar neutrino spectrum, between 9 and 15 MeV. Background free events per year (oscillated)

31. LNGS Scientific Committee – April 8,,2005 31G.Battistoni for the ICARUS Coll. 5) Cosmic neutrinos ICARUS T1800 is a unique instrument, with high sensitive mass, able to detect neutrinos in a wide energy region of interest (from one to thousands MeV) from: Supernovae (SN) Neutron star collapse into black hole Active Galactic Nuclei and GRB (according to some non standard models) The time correlation with other neutrino detectors (LVD, Borexino, SK, SNO) and X- gamma detectors (SWIFT, AGILE) or with international networks (SNEWS, GCN) can reduce the background effects and give reliability to the observations of such phenomena. Number of expected SN events in ICARUS T1800 for inverted (normal) hierarchy

32. LNGS Scientific Committee – April 8,,2005 32G.Battistoni for the ICARUS Coll. Sensitivity for SN search

33. LNGS Scientific Committee – April 8,,2005 33G.Battistoni for the ICARUS Coll. Conclusions 1 T600 is now at LNGS the work to install T600 has started and schedule is being respected We ask for the green light to continue the approved program: building the first T1200 module T600+1 st T1200 = T1800 is an important intermediate step in the path of the complete ICARUS project towards the final mass design and has already the possibility to start a real physics investigation. T600 alone would remain just a demonstrative tool

34. LNGS Scientific Committee – April 8,,2005 34G.Battistoni for the ICARUS Coll. Conclusions T1800 has already important physics discovery capabilities in nucleon decay searches. T1800 already allows to have a new initial investigation with negligible or null experimental systematics of the SubGeV range of atmospheric neutrinos. T1800 has already discovery capability for  appearance, and, as far as  - e transitions are concerned, a factor of 2 of improvement with respect to Chooz limit is already possible We reinforce our convincement that resources must be allocated to obtain an improved neutrino beam: a) increasing intensity, b) a different beam (like CNGS- LE) in a second period. The validity of the project has to be evaluated in the long period. In general it must be put in evidence that T1800 is a fundamental step in the ICARUS programme: beyond the topic of nucleon decay the Liquid Argon technology emerges as a fundamental tool to investigate low energy neutrino physics. The validity of the project has to be evaluated in the long period.