Experimental results of the bundle test QUENCH-19 with FeCrAl claddings

The QUENCH-19 test objective was the comparison of FeCrAl(Y) and ZIRLO™ claddings under similar electrical power and gas flow conditions, simulating an early phase of hypothetical severe accident. In common with the previous QUENCH-15 experiment (performed with ZIRLO™ claddings), the electrical power was the same during pre-oxidation and transient stages. After reaching of the maximum power of 18.12 kW the power value was kept constant during about 2000 s. At the end of this phase the maximal peak cladding temperature of about 1500 °C was reached. Much lower heating rate in comparison to QUENCH-15 was measured. Exceeding 1400 °C sharp increase of hydrogen release rate was observed. The test was terminated with reflood by injecting of about 48 g/s of water from the bundle bottom. The temperatures at all bundle elevations decrease immediately after water injection. The total hydrogen release during the whole test was 9.2 g compared to 47.6 g in the QUENCH-15 test with much shorter high electrical power phase. The videoscope observation showed the damage of several claddings at the bundle elevations between 850 and 1000 mm. The claddings were failed either due to melting (mostly) or by spalling of small annular cladding parts

First results of the bundle test QUENCH-19 with FeCrAl claddings

The QUENCH-19 bundle experiment with FeCrAl(Y) claddings and 4 FeCrAl(Y) spacer grids as well as 8 KANTHAL APM corner rods and KANTHAL APM shroud was conducted at KIT on 29th August 2018. This was performed in cooperation with the Oakridge National Laboratory (ORNL). The test objective was the comparison of FeCrAl(Y) and ZIRLO™ claddings under similar electrical power and gas flow conditions. In common with the previous QUENCH-15 experiment, the bundle was heated by a series of stepwise increases of electrical power from room temperature to a maximum of ≈600 °C in an atmosphere of flowing argon (3.45 g/s) and superheated steam (3.6 g/s). The bundle was stabilised at this temperature, the electrical power being ≈4 kW. During this time the operation of the various systems was checked. In a first transient, the electrical power was controlled with the same electrical power history as the QUENCH-15 test. As a result, the bundle was heated to peak cladding temperature of about 1000 °C reached at about 4000 s. It showed a slowed bundle heating than for the QUENCH-15 bundle (1200 °C reached at about 3000 s). In this test phase about 0.3 g of hydrogen were produced (QUENCH-15: 23.3 g). In the following phase, the power was increased continuously to 18.12 kW (corresponds to maximal power of the QUENCH-15 test). After reaching of this value the power was kept constant during about 2000 s. At the end of this phase the maximal peak cladding temperature of Tpct≈1500 °C was reached. Much lower heating rate in comparison to QUENCH-15 was measured. Exceeding Tpct≈1400 °C sharp increase of hydrogen release rate was observed. Then reflood was initiated at ≈9100 s, connected with switching the argon injection to the top of the bundle, first rapidly filling the lower plenum of the test section with 4 kg of water, and continuing by injecting ≈48 g/s of water. The electrical power was reduced to 4.1 kW during the reflood. A temperature excursion was not observed. The temperatures at all elevations decrease immediately after water injection. The total hydrogen release during the whole test was 9.2 g compared to 47.6 g in the QUENCH-15 test with much shorter high electrical power phase. The videoscope observation of the bundle at the positions of the withdrawn corner rods showed the damage of several claddings at the bundle elevations between 850 and 1000 mm. The claddings were failed either due to interaction with melted thermocouples (mostly) or by spalling of small annular cladding parts

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 of three-dimensional reconstruction for the LAr TPC with a practical application to 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 real data tracks collected during the ICARUS T600 detector operation with the CNGS neutrino beam.Comment: Submitted to Advances in High Energy Physic

Search for anomalies in the {\nu}e appearance from a {\nu}{\mu} beam

We report an updated result from the ICARUS experiment on the search for {\nu}{\mu} ->{\nu}e anomalies with the CNGS beam, produced at CERN with an average energy of 20 GeV and travelling 730 km to the Gran Sasso Laboratory. The present analysis is based on a total sample of 1995 events of CNGS neutrino interactions, which corresponds to an almost doubled sample with respect to the previously published result. Four clear {\nu}e events have been visually identified over the full sample, compared with an expectation of 6.4 +- 0.9 events from conventional sources. The result is compatible with the absence of additional anomalous contributions. At 90% and 99% confidence levels the limits to possible oscillated events are 3.7 and 8.3 respectively. The corresponding limit to oscillation probability becomes consequently 3.4 x 10-3 and 7.6 x 10-3 respectively. The present result confirms, with an improved sensitivity, the early result already published by the ICARUS collaboration

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

Experimental search for the LSND anomaly with the ICARUS detector in the CNGS neutrino beam

We report an early result from the ICARUS experiment on the search for nu_mu to nu_e signal due to the LSND anomaly. The search was performed with the ICARUS T600 detector located at the Gran Sasso Laboratory, receiving CNGS neutrinos from CERN at an average energy of about 20 GeV, after a flight path of about 730 km. The LSND anomaly would manifest as an excess of nu_e events, characterized by a fast energy oscillation averaging approximately to sin^2(1.27 Dm^2_new L/ E_nu) = 1/2. The present analysis is based on 1091 neutrino events, which are about 50% of the ICARUS data collected in 2010-2011. Two clear nu_e events have been found, compared with the expectation of 3.7 +/- 0.6 events from conventional sources. Within the range of our observations, this result is compatible with the absence of a LSND anomaly. At 90% and 99% confidence levels the limits of 3.4 and 7.3 events corresponding to oscillation probabilities of 5.4 10^-3 and 1.1 10^-2 are set respectively. The result strongly limits the window of open options for the LSND anomaly to a narrow region around (Dm^2, sin^2(2 theta))_new = (0.5 eV^2, 0.005), where there is an overall agreement (90% CL) between the present ICARUS limit, the published limits of KARMEN and the published positive signals of LSND and MiniBooNE Collaborations.Comment: 10 pages, 7 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

Precision measurement of the neutrino velocity with the ICARUS detector in the CNGS beam

During May 2012, the CERN-CNGS neutrino beam has been operated for two weeks for a total of 1.8 10^17 pot in bunched mode, with a 3 ns narrow width proton beam bunches, separated by 100 ns. This tightly bunched beam structure allows a very accurate time of flight measurement of neutrinos from CERN to LNGS on an event-by-event basis. Both the ICARUS-T600 PMT-DAQ and the CERN-LNGS timing synchronization have been substantially improved for this campaign, taking ad-vantage of additional independent GPS receivers, both at CERN and LNGS as well as of the deployment of the "White Rabbit" protocol both at CERN and LNGS. The ICARUS-T600 detector has collected 25 beam-associated events; the corresponding time of flight has been accurately evaluated, using all different time synchronization paths. The measured neutrino time of flight is compatible with the arrival of all events with speed equivalent to the one of light: the difference between the expected value based on the speed of light and the measured value is tof_c - tof_nu = (0.10 \pm 0.67stat. \pm 2.39syst.) ns. This result is in agreement with the value previously reported by the ICARUS collaboration, tof_c - tof_nu = (0.3 \pm 4.9stat. \pm 9.0syst.) ns, but with improved statistical and systematic errors.Comment: 21 pages, 13 figures, 1 tabl

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