A. Zalewska

Large underground, liquid based detectors for astro-particle physics in Europe: Scientific case and prospects

This document reports on a series of experimental and theoretical studies conducted to assess the astro-particle physics potential of three future large scale particle detectors proposed in Europe as next generation underground observatories. The proposed apparatuses employ three different and, to some extent, complementary detection techniques: GLACIER (liquid argon TPC), LENA (liquid scintillator) and MEMPHYS (water Cherenkov), based on the use of large mass of liquids as active detection media. The results of these studies are presented along with a critical discussion of the performance attainable by the three proposed approaches coupled to existing or planned underground laboratories, in relation to open and outstanding physics issues such as the search for matter instability, the detection of astrophysical neutrinos and geo-neutrinos and to the possible use of these detectors in future high intensity neutrino beams.

The DELPHI Microvertex detector

The DELPHI Microvertex detector, which has been in operation since the start of the 1990 LEP run, consists of three layers of silicon microstrip detectors at average radii of 6.3, 9.0 and 11.0 cm. The 73728 readout strips, oriented along the beam, have a total active area of 0.42 m2. The strip pitch is 25 μm and every other strip is read out by low power charge amplifiers, giving a signal to noise ratio of 15:1 for minimum ionizing particles. On-line zero suppression results in an average data size of 4 kbyte for Z0 events. After a mechanical survey and an alignment with tracks, the impact parameter uncertainty as determined from hadronic Z0 decays is well described by (69pt)2 + 242 μm, with pt in GeV/c. For the 45 GeV/c tracks from Z0 → μ− decays we find an uncertainty of 21 μm for the impact parameter, which corresponds to a precision of 8 μm per point. The stability during the run is monitored using light spots and capacitive probes. An analysis of tracks through sector overlaps provides an additional check of the stability. The same analysis also results in a value of 6 μm for the intrinsic precision of the detector.

A Si strip detector with integrated coupling capacitors

Abstract A silicon microstrip detector with capacitive coupling of the diode strips to the metallization and with individual polysilicon resistors to each diode has been developed. The detector was tested in a minimum ionizing particle beam showing a performance similar to conventional strip detectors and a spatial resolution of 3.5 μm. Capacitive coupling allows the decoupling of the leakage current from the input to the charge sensitive preamplifier especially in the case of LSI electronics.

The DELPHI silicon strip microvertex detector with double sided readout

The silicon strip microvertex detector of the DELPHI experiment at the CERN LEP collider has been recently upgraded from two coordinates (RΦ only) to three coordinates reconstruction (RΦ and z). The new Microvertex detector consists of 125 952 readout channels, and uses novel techniques to obtain the third coordinate. These include the use of AC coupled double sided silicon detectors with strips orthogonal to each other on opposite sides of the detector wafer. The routing of signals from the z strips to the end of the detector modules is done with a second metal layer on the detector surface, thus keeping the material in the sensitive area to a minimum. Pairs of wafers are daisy chained, with the wafers within each pair flipped with respect to each other in order to minimize the load capacitance on the readout amplifiers. The design of the detector and its various components are described. Results on the performance of the new detector are presented, with special emphasis on alignment, intrinsic precision and impact parameter resolution. The new detector has been taking data since spring of 1994, performing up to design specifications.

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

Abstract The OPERA Collaboration (2011) [1] has reported evidence of superluminal ν μ propagation between CERN and the LNGS. Cohen and Glashow (2011) [2] argued that such neutrinos should lose energy by producing photons and e + e − pairs, through Z 0 mediated processes analogous to Cherenkov radiation. In terms of the parameter δ ≡ ( v ν 2 − v c 2 ) / v c 2 , the OPERA result corresponds to δ ≈ 5 ⋅ 10 − 5 . For this value (note that ( v ν − v c ) / v c ≈ δ 2 ≈ 2.5 ⋅ 10 − 5 ) of δ , 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, as also reported by OPERA. Our results therefore refute a superluminal interpretation of the OPERA result according to the Cohen and Glashow (2011) prediction [2] for a weak current analog to Cherenkov radiation. In a dedicated search, no superluminal Cherenkov-like e + e − pair or γ 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 δ 2.5 ⋅ 10 − 8 at the 90% confidence level, comparable with the one due to the observations from the SN1987a (M.J. Longo, 1987 [4] ). The observations of high energy neutrino events by Super-Kamiokande and IceCube are also pointing to a much stricter limit on δ .

Performance of a liquid argon time projection chamber exposed to the CERN West Area Neutrino Facility neutrino beam

F. Arneodo, P. Benetti, M. Bonesini, A. Borio di Tigliole, B. Boschetti, A. Bueno, E. Calligarich, F. Casagrande, a D. Cavalli, F. Cavanna, P. Cennini, S. Centro, E. Cesana, D. Cline, A. Curioni, b I. De Mitri, C. De Vecchi, 2 R. Dolfini, A. Ferrari, A. Ghezzi, A . Guglielmi, J. Kisiel, G. Mannocchi, A. Mart́ınez de la Ossa, C. Matthey, F. Mauri, C. Montanari, S. Navas, P. Negri, M. Nicoletto, S. Otwinowski, M. Paganoni, O. Palamara, A. Pepato, L. Periale, G. Piano Mortari, P. Picchi, 5 F. Pietropaolo, A. Puccini, A. Pullia, S. Ragazzi, T. Rancati, A. Rappoldi, G.L. Raselli, N. Redaelli, E. Rondio, A. Rubbia, C. Rubbia, P.R. Sala, F. Sergiampietri, J. Sobczyk, S. Suzuki, 5, c T. Tabarelli de Fatis, M. Terrani, F. Terranova, A. Tonazzo, S. Ventura, C. Vignoli, H. Wang, and A. Zalewska

Beam test results from a prototype for the delphi microvertex detector

Abstract Results are presented from a test in the CERN SPS North Area of a prototype of the DELPHI microvertex detector. Full-sized modules built up from prototype ac-coupled detectors and VLSI readout electronics were used. The spatial resolution of the detectors equipped with prototype VLSI chips was measured to be 6.5 μm. The system aspects, including the readout, were found to work well. Extrapolating to the final components we expect to achieve a measurement precision of 5 μm with the DELPHI microvertex detector.

The T2K Side Muon Range Detector (SMRD)

The T2K experiment is a long baseline neutrino oscillation experiment aiming to observe the appearance ofe in a �µ beam. The �µ beam is produced at the Japan Proton Accelerator Research Complex (J-PARC), observed with the 295 km distant Super- Kamiokande Detector and monitored by a suite of near detectors at 280m from the proton target. The near detectors include a magnetized off-axis detector (ND280) which measures the un-oscillated neutrino flux and neutrino cross sections. The present paper describes the outermost component of ND280 which is a side muon range detector (SMRD) composed of scintillation counters with embedded wavelength shifting fibers and Multi-Pixel Photon Counter read-out. The components, performance and response of the SMRD are presented.

Silicon ultra fast cameras for electron and γ sources in medical applications

Abstract SUCIMA (Silicon Ultra fast Cameras for electron and γ sources In Medical Applications) is a project approved by the European Commission with the primary goal of developing a real time dosimeter based on direct detection in a Silicon substrate. The main applications, the detector characteristics and technologies and the data acquisition system are described.

Precise 3D Track Reconstruction Algorithm for the ICARUS T600 Liquid Argon Time Projection Chamber Detector

Liquid Argon Time Projection Chamber (LAr TPC) detectors offer charged particle imaging capability with remarkable spatial resolution. Precise event reconstruction procedures are critical in order to fully exploit the potential of this technology. In this paper we present a new, general approach to 3D reconstruction for the LAr TPC with a practical application to the track reconstruction. The efficiency of the method is evaluated on a sample of simulated tracks. We present also the application of the method to the analysis of stopping particle tracks collected during the ICARUS T600 detector operation with the CNGS neutrino beam.