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Posters part D: 1 – Neutrinos in ICARUS; 2 – RENO-50

March 14, 2013

Here are two more poster summaries. Thanks to the submitters!

1 – Dorota Stefan: Neutrino Reconstruction in ICARUS

Liquid Argon TPC imaging technique gives the unique view of the particle
interactions, often compared to the old bubble chamber analogue era.
Recorded information is so reach in details that special reconstruction
algorithms had to be developed and some aspects are still challenge. In
these days the progress becomes fast around the world – full size
detectors appear and data is coming. Among the competitors, the ICARUS
detector is the biggest one, with the ability to capture full contained
neutrino events with all their variety and complexity.
The detection concept is: charged particle traversing liquid Ar produces
ionization electrons along its path. Ionization electrons are drifting in
the uniform electric field toward anode. ADC(t) signals on the readout
wires of the anode forms two-dimensional projection of the particle track.
Association of projections obtained from wire planes (two induction-mode
and one collection-mode, with different wire orientations) allows 3D
spatial reconstruction; collection plane signal provides calorimetric
information. Excellent granularity of 2D images comes at the price of
complex image recognition problem.

The poster presents the method of the neutrino event reconstruction in the
ICARUS detector. The reconstruction starts from the signal reconstruction,
called hit reconstruction, next, the event has to be clusterized in 2D
projections and finally the information from projections is used to
reconstruct 3D objects such as track and cascades. The hit reconstruction
is used to the event energy deposition analysis. Nowadays the 2D
clustering method is developed putting emphasis on the recognition between cascades
and tracks. Those objects had to be recognzied in each projections
independly. After that the automatization of the 3D event reconstruction
can be applied by association of objects in complementary wire planes. The
novel 3D reconstruction in LAr TPC detector, which has been published
yesterday, gives us the high precision required eg for the particle
identification. An example of this is shown on stopping protons, kaon,
pions and also on the recognition between cascades initiated by electrons
and photons.


2 – Jungsic Park: Study of Neutrino Mass Hierarchy at RENO-50. 

A 5 kton of ultra-low-radioactivity liquid scintillator detector, located at roughly 50 km away from the Yonggwang nuclear power plant, is proposed to determine the neutrino mass hierarchy where the neutrino oscillation due to theta_12 takes place at maximum with the baseline. The detector is expected to detect neutrinos from nuclear reactors, the Sun, Supernova, the Earth, any possible stellar object and the J-PARC neutrino beam. It could be regarded as a multi-purpose and long-term operational detector.

The main goal is to measure the most accurate value of theta_12 and mass squared difference, and to attempt determination of the neutrino mass hierarchy. We will describe physics goals and experimental arrangement of RENO-50 shortly and present its sensitivity based on a MC study, especially focused on the possibility of mass hierarchy. To measure mass hierarchy, the PMT coverage should reach more than 30% to get 3% of energy resolution, in the assumption that other properties like attenuation length of liquid scintillator, target vessel material (possibly acrylic), and light yield are comparable to RENO. In the real experiment, we consider the bin size of ~12bin/MeV and 3% energy resolution. With this bin size, we generated events for normal hierarchy and calculate chi-square based on the hypotheses of normal hierarchy or inverted hierarchy.

The MC simulation result shows that at least 60000 events for 3sigma determination is necessary, and thus needs ~40 years of data-taking for RENO-50 (10 years for 20kton detector). In conclusion, a large (>20 kton) detector with 3% energy resolution is needed to determine mass hierarchy within 10 years and modular detector components are highly recommended because of the attenuation length of liquid scintillator.


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