A new, very massive modular Liquid Argon Imaging Chamber to detect low energy off-axis neutrinos from the CNGS beam. (Project MODULAr)

The paper is considering an opportunity for the CERN/GranSasso (CNGS) neutrino complex, concurrent time-wise with T2K and NOvA, to search for theta_13 oscillations and CP violation. Compared with large water Cherenkov (T2K) and fine grained scintillators (NOvA), the LAr-TPC offers a higher detection efficiency and a lower backgrounds, since virtually all channels may be unambiguously recognized. The present proposal, called MODULAr, describes a 20 kt fiducial volume LAr-TPC, following very closely the technology developed for the ICARUS-T60o, and is focused on the following activities, for which we seek an extended international collaboration: (1) the neutrino beam from the CERN 400 GeV proton beam and an optimised horn focussing, eventually with an increased intensity in the framework of the LHC accelerator improvement program; (2) A new experimental area LNGS-B, of at least 50000 m3 at 10 km off-axis from the main Laboratory, eventually upgradable to larger sizes. A location is under consideration at about 1.2 km equivalent water depth; (3) A new LAr Imaging detector of at least 20 kt fiducial mass. Such an increase in the volume over the current ICARUS T600 needs to be carefully considered. It is concluded that a very large mass is best realised with a set of many identical, independent units, each of 5 kt, "cloning" the technology of the T600. Further phases may foresee extensions of MODULAr to meet future physics goals. The experiment might reasonably be operational in about 4/5 years, provided a new hall is excavated in the vicinity of the Gran Sasso Laboratory and adequate funding and participation are made available.Comment: Correspondig Author: C. Rubbia (E-mail: [email protected]), 33 pages, 11 figure

A search for the analogue to Cherenkov radiation by high energy neutrinos at superluminal speeds in ICARUS

The OPERA collaboration has claimed evidence of superluminal {\nu}{_\mu} propagation between CERN and the LNGS. Cohen and Glashow argued that such neutrinos should lose energy by producing photons and e+e- pairs, through Z0 mediated processes analogous to Cherenkov radiation. In terms of the parameter delta=(v^2_nu-v^2_c)/v^2_c, the OPERA result implies delta = 5 x 10^-5. For this value of \delta a very significant deformation of the neutrino energy spectrum and an abundant production of photons and e+e- pairs should be observed at LNGS. We present an analysis based on the 2010 and part of the 2011 data sets from the ICARUS experiment, located at Gran Sasso National Laboratory and using the same neutrino beam from CERN. We find that the rates and deposited energy distributions of neutrino events in ICARUS agree with the expectations for an unperturbed spectrum of the CERN neutrino beam. Our results therefore refute a superluminal interpretation of the OPERA result according to the Cohen and Glashow prediction for a weak current analog to Cherenkov radiation. In particular no superluminal Cherenkov like e+e- pair or gamma emission event has been directly observed inside the fiducial volume of the "bubble chamber like" ICARUS TPC-LAr detector, setting the much stricter limit of delta < 2.5 10^-8 at the 90% confidence level, comparable with the one due to the observations from the SN1987A.Comment: 17 pages, 6 figure

Underground operation of the ICARUS T600 LAr-TPC: first results

Open questions are still present in fundamental Physics and Cosmology, like the nature of Dark Matter, the matter-antimatter asymmetry and the validity of the particle interaction Standard Model. Addressing these questions requires a new generation of massive particle detectors exploring the subatomic and astrophysical worlds. ICARUS T600 is the first large mass (760 ton) example of a novel detector generation able to combine the imaging capabilities of the old famous "bubble chamber" with an excellent energy measurement in huge electronic detectors. ICARUS T600 now operates at the Gran Sasso underground laboratory, studying cosmic rays, neutrino oscillation and proton decay. Physical potentialities of this novel telescope are presented through few examples of neutrino interactions reconstructed with unprecedented details. Detector design and early operation are also reported.Comment: 14 pages, 8 figures, 2 tables. Submitted to Jins

Measurement of Through-Going Particle Momentum By Means Of Multiple Scattering With The ICARUS T600 TPC

The ICARUS collaboration has demonstrated, following the operation of a 600 ton (T600) detector at shallow depth, that the technique based on liquid Argon TPCs is now mature. The study of rare events, not contemplated in the Standard Model, can greatly benefit from the use of this kind of detectors. In particular, a deeper understanding of atmospheric neutrino properties will be obtained thanks to the unprecedented quality of the data ICARUS provides. However if we concentrate on the T600 performance, most of the $\nu_\mu$ charged current sample will be partially contained, due to the reduced dimensions of the detector. In this article, we address the problem of how well we can determine the kinematics of events having partially contained tracks. The analysis of a large sample of atmospheric muons collected during the T600 test run demonstrate that, in case the recorded track is at least one meter long, the muon momentum can be reconstructed by an algorithm that measures the Multiple Coulomb Scattering along the particle's path. Moreover, we show that momentum resolution can be improved by a factor two using an algorithm based on the Kalman Filtering technique

Towards a new Liquid Argon Imaging Chamber for the MODULAr project

The MODULAr project foresees the exploitation of a new liquid Argon imaging detector, of at least 20 kt fiducial mass, to be operated in a shallow depth location under the Gran Sasso Mountain. It will be devoted to study neutrino oscillations with an optimized off-axis CNGS neutrino beam. Cosmic neutrinos as well as proton decay will also be addressed. The MODULAr detector will vastly inherit from the technology developed for ICARUS-T600. However, such an increase in the volume over the current ICARUS-T600 needs to be carefully considered. It is concluded that a single, huge volume is an inoperable and uneconomical solution for many reasons. A very large mass is best realized with a modular set of many identical, independent units, each of about 5 kt, "cloning" the basic technology of the ICARUS-T600. Several of such modular units will be assembled to reach at least 20 kt as initial sensitive volume. The increase of the active volume of about one order of magnitude with respect to the ICARUS-T600 detector requires some specific R&D activity, which will be implemented in a similar to 360 ton prototype unit (SLICE) of reduced length

Measurement of the muon decay spectrum with the ICARUS liquid Argon TPC

Examples are given which prove the ICARUS detector quality through relevant physics measurements. We study the muon decay energy spectrum from a sample of stopping muon events acquired during the test run of the ICARUS T600 detector. This detector allows the spatial reconstruction of the events with fine granularity, hence, the precise measurement of the range and dE/dx of the muon with high sampling rate. This information is used to compute the calibration factors needed for the full calorimetric reconstruction of the events. The Michel rho parameter is then measured by comparison of the experimental and Monte Carlo simulated muon decay spectra, obtaining rho = 0.72 +/- 0.06(stat.) +/- 0.08(syst.). The energy resolution for electrons below ~50 MeV is finally extracted from the simulated sample, obtaining (Emeas-Emc)/Emc = 11%/sqrt(E[MeV]) + 2%.Comment: 16 pages, 8 figures, LaTex, A4. Some text and 1 figure added. Final version as accepted for publication in The European Physical Journal

The ICARUS Experiment, A Second-Generation Proton Decay Experiment and Neutrino Observatory at the Gran Sasso Laboratory

The final phase of the ICARUS physics program requires a sensitive mass of liquid Argon of 5000 tons or more. The T600 detector stands today as the first living proof that such large detector can be built and that liquid Argon imaging technology can be implemented on such large scales. After the successful completion of a series of technical tests to be performed at the assembly hall in Pavia, the T600 detector will be ready to be transported into the LNGS tunnel. The operation of the T600 at the LNGS will allow us (1) to develop the local infrastructure needed to operate our large detector (2) to start the handling of the underground liquid argon technology (3) to study the local background (4) to start the data taking with an initial liquid argon mass that will reach in a 5-6 year program the multi-kton goal. The T600 is to be considered as the first milestone on the road towards a total sensitive mass of 5000 tons: it is the first piece of the detector to be complemented by further modules of appropriate size and dimensions, in order to reach in a most efficient and rapid way the final design mass. In this document, we describe the physics program that will be accomplished within the first phase of the program

Energy reconstruction of electromagnetic showers from [Pi 0] decays with the ICARUS T600 liquid argon TPC

We discuss the ICARUS T600 detector capabilities in electromagnetic shower reconstruction through the analysis of a sample of 212 events, coming from the 2001 Pavia surface test run, of hadronic interactions leading to the production of 0 mesons. Methods of shower energy and shower direction measurements were developed and the invariant mass of the photon pairs was reconstructed. The ( ) invariant mass was found to be consistent with the value of the 0 mass. The resolution of the reconstructed 0 mass was found to be equal to 27.3%. An improved analysis, carried out in order to clean the full event sample from the events measured in the crowded environment, mostly due to the trigger conditions, gave a 0 mass resolution of 16.1%, significantly better than the one evaluated for the full event sample. The trigger requirement of the coincidence of at least four photo-multiplier signals favored the selection of events with a strong pile up of cosmic ray tracks and interactions. Hence a number of candidate 0 events were heavily contaminated by other tracks and had to be rejected. Monte Carlo simulations of events with 0 production in hadronic and neutrino interactions confirmed the validity of the shower energy and shower direction reconstruction methods applied to the real data

Improving the performance of the liquid argon TPC with tetra-methyl-germanium NUCLEAR INSTRUMENTS &amp;METHODS IN PHYSICS RESEARCH by doping

Abstract In order to recover the charge lost by electron-ion recombination, we doped pure liquid argon with a photosensitive hydrocarbon, tetra-methyl-germanium (TMG). in the 3 ton ICARUS TPC. A charge increase of 25% to 220% was observed for different electric fields and for energy densities ranging from I .6 to 32 MeV/cm. The 3 ton liquid argon TPC has been in operation since May 1991 with pure liquid argon (LAr). In these three years we measured the basic parameters of the detector responses, such as the spatial resolution, the electron diffusion coefficient, the correlation of collected charge with electric field and energy density, by cosmic rays and external gamma ray sources [I]. In addition we have been continuously monitoring the stability of the liquid argon purity, the effectiveness of the recirculation system. and the reliabiIity of the electronics read-out. So far no degradation of any part of this detector has been found. As is well known, an ionizing particle in liquid argon will produce electron-ion pairs and excitons along the track. Depending on the ionization density and electric field, some of the pairs recombine and emit vacuum ultraviolet (VUV) photons with energy distribution peaked at 128 nm (9.7 eV). On the other hand, photon emission from excitons exhibits energy distribution peaking at the same energy (9.7 eV). With our data by minimum ionizing muons (mip), stopping muons and stopping protons, we have measured the coliected charge as a function of energy density 11.6 to 32 MeV/cm) and electric field (100 to 500 V/cm) in pure liquid argon. We found that the electron escape probability depends heavily on these two parameters. The percentage of free electron yield can vary from 70% to 14% at different energy densities and electric fields. This nonlinear detector response may degrade the particle identification capability of the liquid argon TPC. A possible solution to improve the linearity of the detector response is to introduce photosensitive dopants able to convert part of the scintillation light, either from electronion recombination or by direct excitation, into additional free electron-ion pairs, thus enhancing the linearity as a function of the deposited energy density and electric field. We chose TMG as photosensitive dopant because of the following advantages

Observation of long ionizing tracks with the ICARUS T600 first half-module

F. Arneodo, B. Bade"ek, A. Badertscher, B. Baiboussinov, M. Baldo Ceolin, G. Battistoni, B. Bekman, P. Benetti, E. Bernardini, M. Bischofberger, A. Borio di Tigliole, R. Brunetti, A. Bueno, E. Calligarich, M. Campanelli, C. Carpanese, D. Cavalli, F. Cavanna, P. Cennini, S. Centro, A. Cesana, C. Chen, D. Chen, D.B. Chen, Y. Chen, D. Cline, Z. Dai, C. De Vecchi, A. Dabrowska, R. Dolfini*, M. Felcini, A. Ferrari, F. Ferri, Y. Ge, A. Gigli Berzolari, I. Gil-Botella, K. Graczyk, L. Grandi, K. He, J. Holeczek, X. Huang, C. Juszczak, D. Kie"czewska, J. Kisiel, T. Koz"owski, H. Kuna-Ciska", M. Laffranchi, J. Łagoda, Z. Li, F. Lu, J. Ma, M. Markiewicz, A. Martinez de la Ossa, C. Matthey, F. Mauri, D. Mazza, G. Meng, M. Messina, C. Montanari, S. Muraro, S. Navas-Concha, M. Nicoletto, G. Nurzia, S. Otwinowski, Q. Ouyang, O. Palamara, D. Pascoli, L. Periale, G. Piano Mortari, A. Piazzoli, P. Picchi, F. Pietropaolo, W. P ! o"ch"opek, T. Rancati, A. Rappoldi, G.L. Raselli, J. Rico, E. Rondio, M. Rossella, A. Rubbia, C. Rubbia, P. Sala, D. Scannicchio, E. Segreto, F. Sergiampietri, J. Sobczyk, J. Stepaniak, M. Szeptycka, M. Szleper, M. Szarska, M. Terrani, S. Ventura, C. Vignoli, H. Wang, M. W ! ojcik, J. Woo, G. Xu, Z. Xu, A. Zalewska, J. Zalipska, C. Zhang, Q. Zhang, S. Zhen, W. Zipper a INFN Laboratori Nazionali del Gran Sasso, s.s. 17bis Km 18+910, Assergi (L'Aquila), Italy b Institute of Experimental Physics, Warsaw University, Warszawa, Poland c Institute for Particle Physics, ETH H . onggerberg, Z . urich, Switzerland Dipartimento di Fisica e INFN, Universit " a di Padova, via Marzolo 8, Padova, Italy Dipartimento di Fisica e INFN, Universit " a di Milano, via Celoria 16, Milano, Italy f Institute of Physics, University of Silesia, Katowice, Poland Dipartimento di Fisica e INFN, Universit " a di Pavia, via Bassi 6, Pavia, Italy Dpto de F!isica Te ! orica y del Cosmos & C.A.F.P.E., Universidad de Granada, Avda. Severo Ochoa s/n, Granada, Spain Dipartimento di Fisica e INFN, Universit " a dell'Aquila, via Vetoio, L'Aquila, Italy CERN, CH-1211 Geneva 23, Switzerland Politecnico di Milano (CESNEF), Universit " a di Milano, via Ponzio 34/3, Milano, Ital