Program

The recent demonstrations of oscillations in the atmospheric and solar neutrino data convincingly indicate that neutrinos do have mass. Those data however, do not tell us the absolute mass scale but only the differences of the square of the neutrino masses. Even so, we now know that at least one neutrino has a mass of about 50 meV or larger.

Studies of double beta decay rates offer hope for determining the absolute mass scale. In particular, zero-neutrino double beta decay can address the issues of lepton number conservation, the particle-antiparticle nature of the neutrino, and its mass. In fact, upcoming generations of double-beta decay experiments will be sensitive to neutrino masses in the exciting range of below 50 meV. An overviewof double-beta decay and its relation to neutrino mass will be discussed followed by a profile of a overall double-beta decay program. In this presentation, I will summarize the physics goals for double-beta decay experiments and the experimental issues that require attention to ensure that the proposed experiments reach these goals.

Germanium detectors enriched in Ge76 are one of the most promising techniques to search for neutrinoless double-beta decay. This talk will review this technique and provide an update of the Majorana experiment that proposes to field 30-60 kg. of enriched detectors in a prototype module. This module will be an intermdiate phase towards the realization of a tonne-scale enriched germanium experiment.

We would like to present current status of our CANDLES detector system for the study of 48Ca double beta decay.

The neutrinoless double beta decay (0nu2beta) searches are one of the modern key experiments as they constitute a test of the standard model. This process is similar to the normal 2nu2beta decay, however without emission of neutrinos thus violating the lepton number by Delta L = 2. Consequently, this process leads beyond the standard model as it requires non-zero neutrino masses of Majorana type and violates the conservation of lepton numbers. From theexistence of the 0nu2beta decay and much more from the details of the process we will get answers e.g. about the hierarchy, but also beyond neutrino physics open problems e.g. in cosmology will be solved.

Only a few nuclei are suitable for the investigation of the 0nu2beta process. 76Ge is outstanding as two experiments, the Heidelberg-Moscow and the Igex, have reported lower limits of the half-time of about T_{1/2} >!23$ 1,6 10^{25} y which corresponds to effective Majorana masses of (0.33--1.35) eV. The results remain controversial as part of the HdM group has claimed a lower central value of 0.44~eV obtained from the same data set. Sofar, the results for other isotopes (Couricino or Nemo) could neither confirm the claim of observing a 0nu2beta decay, nor exclude it.

A new 76Ge experiment is needed to establish unequivocally the signal with an improved sensitivity at lower background rates, or refute it with high significance. The experimental signature for the 0nu2beta process is the observation of a peak at the value of Q_{betabeta} in the electron spectrum. Ge-diodes enriched to 86% in 76Ge serve as source and as detectors. The GERDA Collaboration at present prepares a new setup at LNGS, where the bare diodes will be operated in a big tank of liquid argon which itself sit in a large water tank. This reduction of high-Z material and active vetos reduce the remaining muon-induced background!23$ a careful selection of materials after radioassessment will improve the background level further. Finally, a background level of is envisaged.

In Phase I about 18 kg of enriched detectors available from the HdM and Igex experiments will be used. In phase II, new detectors with segmented electrodes will be added doubling the target mass. After an exposure of 100 kgy we expect a sensitivity of T_{1/2}>!23$ 1,4 10^{26}$ y at 90 % confidence level. A later phase will employ additional segmented diodes which intrinsically improve the rejection of background. Depending on the results, a phase III with about 500 kg target mass is conceived probing the few 10 meV mass range.

The status of the experiment and the ongoing tests will be presented.

The Enriched Xenon Observatory (EXO) is an experiment aimed at measuring the half life for neutrinoless double beta decay (0vBB) of 136Xe. A xenon-filled time projection chamber (TPC) supplemented with scintillation light readout detects ionizing particle interactions within its volume. Candidate 0vBB events will be distinguished from virtually all radioactive background by positively identifying the 136Ba daughter for each event via optical spectroscopy. The EXO collaboration is pursuing a phased approach toward a ton-scale detector. A smaller detector, EXO-200, using 200 kg of enriched Xe (80% 136Xe) with no 136Ba identification is currently in advanced stages of commissioning at Stanford University. Its deployment underground at the Waste Isolation Pilot Plant (WIPP) in New Mexico is planned to begin in the summer of 2007. In parallel, various strategies for 136Ba tagging are being developed in the laboratory. I will present the EXO experiment in the context of 0vBB searches, and describe the EXO-200 detector in detail, discussing its physics goals, experimental challenges, and schedule. I will also illustrate some of the most promising approaches for efficient tagging of single 136Ba ions produced in a ton-scale Xe detector, show milestone results achieved in laboratory setups, and discuss the EXO timeline for the near future.

XMASS is a multi-purpose experiment using liquid xenon which aims at the detection of cold dark matter, search for neutrinoless double beta decay, and detetion of low energy solar neutrinos. R&D efforts for the double beta decay experiment of XMASS is presented. Because of the high scintillation light yield of the liquid xenon, it is possible to achieve good energy resolution for discriminating 2nu2beta and 0nu2beta of 136Xe if we can collect scintillation light with high collection efficiency. However, because of the high radioactive contamination of photomultiplier tubes (PMTs), we cannot put the PMTs very close to the liquid scinitillator. In order to achieve high light collection efficiency but keeping PMTs away from the liquid xenon, we have designed a detector using an ELliptic water Tank(ELT). The inner surface of the ELT is made of mirror and liquid xenon enclosed in a vessel with high pressure (since it is room temperature) is placed at one focus of the ELT. The scinillation light emitted in the liquid xenon is wavelength shifted at the inner surface of the vessel and transmitted to another focus through water filled in ELT. The PMTs are placed at the focus and it enable us to collect photons with high efficiency with small number of PMTs. The water between focuses reduces gamma ray background from the PMTs. R&D stauts of (1) scintillation light yeild under high pressure, room tmperature liquid xenon, (2) development of a wavelength shifter, and (3) study on the light collection of ELT, are reported.

The KArlsruhe TRItium Neutrino experiment aims to determine the mass of the electron antineutrino in a model-independent way from the kinematics of tritium beta-decay. It combines a gaseous windowless tritium source with a column density of 5 x 10^17 molecules/cm^2 with a high resolution electrostatic retarding spectrometer (MAC-E filter) to measure the spectral shape of the beta electron energy spectrum close to the endpoint at 18.6 keV with unprecedented precision.

KATRIN's sensitivity to the neutrino mass will be 0.2 eV/c^2 after 3 years of full data taking. In case no neutrino mass signal is observed this number corresponds to an upper limit with 90% confidence level!23$ the signature ofa neutrino mass of 0.35 eV could be determined with 5 sigma significance.

To reach this sensitivity, a stringent suppression of all sources of background and a careful monitoring of the long term stability of the instrument are two of the most important issues. One of the major sources of background are electrons produced by cosmic muons and intrinsic radioactivity in the spectrometer material. To prevent these electrons from entering the inner part of the spectrometer a double layer wire electrode on negative potential will be mounted inside the spectrometer vessel. For monitoring of the retardation potential with ppm accuracy a special high voltage divider has been developed in close collaboration with the german metrological institute (PTB Braunschweig). An additional smaller spectrometer will be driven by the same high voltage as the main spectrometer and will provide a natural standard by monitoring the K-32 conversion line of a 83mKr source.

The KATRIN experiment is presently being set up at the Forschungszentrum Karlsruhe (FZK) by an international collaboration, making use of the capabilities of the existing tritium laboratory. The main spectrometer vessel has successfully passed first vacuum tests at the manufacturer and has been transported to FZK in autumn 2006.

The actual status of the construction and of test measurements will be presented.

The work of the author is supported by the German Federal Ministry of Education and Research (BMBF).

We report the first results from a search for Weakly Interacting Massive Particles (WIMPs) with the XENON10 experiment operating underground at the Gran Sasso Laboratory. XENON10 is the first dual phase (liquid/gas) xenon time projection chamber (XeTPC) module realized within the XENON program. The 3D-postion sensitive detector has an active mass of 15 kg of liquid xenon, viewed by two arrays of compact photomultipliers, which measure simultaneously the scintillation and the ionization, via proportional scintillation in the gas. Background rejection on an event-by-event basis is achieved through this measurement and 3D event localization. In-situ gamma and neutron calibrations have been carried out to define event selection and energy threshold for nuclear recoil candidates. A ' blind ' analysis of ~60 live-days of Dark Matter Search science data has been performed. Results of this analysis will be presented. Plans to improve the experiment sensitivity within 2007 as well as plans to initiate the next phase of the XENON program with a 100kg scale TPC will also be addressed.

We plan a direction-sensitive dark matter search experiment with a gaseous time projection chamber. We developed a prototype TPC with a volume of 30*30*30cm^3. We are reporting the performance of the TPC and reluts of a direction-sensitive dark matter search experiment in a surface laboratory.

The PICO-LON (Planar Inorganic Crystals for LOw-background Neutr(al)ino) consists of many layers of NaI(Tl) scintillator. The sensitivity of PICO-LON for dark matter and the recent progress of underground experiment at OTO Cosmo Observatory is presented.

We first briefly discuss how absolute neutrino mass of about 1 eV affects cosmological observables such as CMB power spectrum and show that a subelectronvolt upper limit can be obtained from the current observations such as WMAP. Then we discuss how cosmological parameter estimation, especially for the hubble parameter, is affected by non-zero neutrino mass.

The IceCube telescope is aimed to detect very high energy neutrinos from cosmological sources such as AGNs and GRBs. The telescope is being deployed in the Antarctica glacier. It detects Cherenkov lights from particles that are induced by a neutrino. Approximately one third of the detectors (22 strings) have been installed, and they areoperational. The status of the IceCube telescope and the astrophysical application will be presented.

The Borexino detector will spectroscopically measure the Be-7 neutrinos from the Sun for the first time. This energy region provides a sensitive probe for new physics, and also a chance to explore the transition region between vacuum and matter oscillations predicted in the MSW mechanism.

The detector is now complete, and data collection has begun. To confirm the solar origin of any observed Be-7 neutrinos via the annual variation due to orbital eccentricity, or to obtain an absolute flux, stable and absolute calibration of the detector's fiducial volume is essential. While the former can be obtained continuously via normalization to the C-14 spectra or other known features, the latter requires an internal source with absolute position accuracy of about 2 cm.

This talk will describe the physics goals, the state of the detector hardware, and the approach being taken to calibrate the detector with the required accuracy. Techniques used to confirm absolute source position capabilities (typically one of the largest systematic errors in an absolute measurement) will be described.

The KamLAND experiment gives precise measurement of neutrino oscillation parameters using reactor anti-neutrinos. Due to their clear spectral distortion, the neutrino mass difference determined with about 5% precision. In order to get a better sensitivity, we are now planning to reduce systematic uncertainties using full volume calibration. That will be helpful also for the geo anti-neutrino measurement in lower energy region. In addition, I will also discuss a possibility of double beta decay experiment using the KamLAND detector in future.

A complete spectral measurement of the solar neutrino flux with LENS will allow to test current standard and non standard neutrino flavor conversion models along with the solar model in one experiment. Probing the temperature profile of nuclear fusion in the sun and a search for active - sterile neutrino oscillations add to the multi-faceted physics program envisioned. This talk will describe the science and technology of LENS, and the steps being taken to create mini-LENS, a full-fledged prototype of the LENS detector.

I review why neutrinos have been an exciting topic in physics, astrophysics and cosmology, and how we may pursue it further.

The idea of the COBRA project is the search for neutrion-less double beta decay with the help of CdZnTe semiconductor detectors [1]. In its final stage the experiment aims to run 420 kg of CdZnTe detectors enriched in the isotope 116Cd, resulting in a neutrino mass sensitivity of around 50 meV.

CdZnTe detectors contain several double beta emitters including those decaying via positron emission or electron capture. Four 1 cm**3 CZT detectors were operated in the Gran Sasso Underground Facility (LNGS) from 2004-2006. First half life limits were obtained including new world best limits for 0vECEC ground state transitions of 64Zn and 120Te [2]. An additional measurement of the 4-fold forbidden non-unique beta decay of 113Cd has been performed and resulted in a half-life of 8.20 x 10**15 yrs [3].

Since Spring 2006 an upgrade to 64 detectors, corresponding to a mass of about 0.42 kg, is being installed, with the first 16 running at LNGS. Independent of the low background studies performed at LNGS, the option of using pixelated CZT detectors is being explored. The tracking capabilities of such a device offers a massive background reduction due to particle identification. First simulations suggest an improvement by three orders of magnitude [4]. Furthermore, a sophisticated shielding has been designed for a large scale experiment, able to reduce neutron and gamma backgrounds to an acceptable level [5].

[1] K.Zuber, Phys.Lett.B 519 (2001)
[2] T.Bloxham et al., subm. to Phys.Rev.C
[3] C.Goesling et al., Phys.Rev.C 72 (2005) 064328
[4] T.Bloxham and M.Freer, acc. by Nucl.Inst.Meth. A, 2007
[5] D.Stewart et al., acc. by Nucl.Inst.Meth. A,2007

DCBA (Drift Chamber Beta-ray Analyzer) has been developed at KEK in order to search for neutrinoless double beta decay. It consists of drift chambers, a solenoid magnet and cosmic ray veto-counters. A prototype called DCBA-T2 has been constructed and operated. A new test apparatus called DCBA-T3 has been designed to improve energy resolution and now under construction. Test results of DCBA-T2 and the design parameters of DCBA-T3 will be presented.

This talk will describe the developments of a Nd-loaded liquid scintillator for the SNO detector. The properties of the Nd liquid scintillator, and the sensitivity of this experiment will be presented.

First results of a $\nu_{\mu} \to \nu_{e}$ oscillation search in MiniBooNE (Booster Neutrino Experiment) experiment will be reported. If an appearance signal is observed, it will imply Physics Beyond the Standard Model such as the existence of light sterile neutrino.

Current status on OPERA experiments will be presented.

Electric detector installation have been finished, and performnace have been confirmed by cosmic rays and by neutrino exposure. Several performance test for event location in ECC target　 was done by 2006 short period neutrino beam exposure. Now active neutrino target,ECC bricks are installing toward for starting real RUN in this autumn exposure.

Status on preparartions and some test results will be reported.

T2K (Tokai-to-Kamioka) experiment is a next generation long baseline neutrino oscillation experiment in Japan. An intense narrow-band beam of muon-neutrino is produced by using 50 GeV proton synchrotron in J-PARC (Japan Proton Accelerator Research Complex), and is directed to the Super-Kamiokande detector located at 295 km from J-PARC.

The main physics goals of the T2K experiment are to discover a finite $¥theta_{13}$ by observing $¥nu_e$ appearance ($¥nu_{¥mu} ¥to ¥nu_e$ oscillation), and to precisely measure oscillation parameters in $¥numu$ disappearance.

One of the most significant merits of the T2K experiment is the intense narrow-band neutrino beam produced by employing 'off-axis' method. This method will enhance the experiment sensitivity by allowing tuning of the beam energy to match with neutrino oscillation maximum. In order to maximize the sensitivity to $¥Delta m_{23}^2 = (2 ¥sim 3 ) ¥times 10^{-3}$ eV$^2$, we adjust neutrino energy to be between 0.5 GeV and 0.7 GeV by setting the off-axis angle to be between $2^¥circ$ and $2.5^¥circ$.

The neutrino beamline is now under construction at J-PARC. Commissioning of the beam will start in the spring of 2009. In this presentation, we will report the status of, and prospects for the T2K experiment.

Double Chooz is a next generation reactor theta-13 experiment being constracted in France. The experiment starts data taking in 2008, which is the quickest to explore the theta-13 below current Chooz limit. The sensitivity is sin22thata_13 ~ 0.025.
The speaker talks about the constrcution status of theDouble Chooz experiment as well as its general descriptions.

RENO is a reactor neutrino experiment in Korea to measure theta_13 with a goal of starting taking data in 2010. We will present the general description and current status of the experiment.