##### CUORE

Collaboration:

- Italy: Firenze Univ. and INFN, Insubria Univ. and INFN Milano, LNGS, Milano Univ. and INFN
- Germany: Leiden
- Spain: Zaragoza
- USA: Berkeley, U.C. South Carolina

Location of the experiment: LNGS for cryogenic measurements, Milano-Bicocca for Radioactivity Measurements and Lawrence Berkeley Laboratory for the thermistor production and optimization

National Responsible: E. Fiorini (Mi)

1. Goal of the experiment

CUORE is the acronym for "Cryogenic Underground Observatory for Rare Events". It consists in a series of experiments with very massive cryogenic detectors to investigate rare processes like double beta decay, interactions of Weakly Interacting Massive Particles (WIMPS) and solar axions and to search for rare nuclear decays.

More on the experiment…

2.

Activities during 2001

In this year the group has obtained with the 20 TeO2 crystal array a lower limit of 2 x 1023 years for the neutrinoless double beta decay, the most sensitive to the neutrino mass after the 76Ge ones. The new bolometers with 5x5x5 cm3 crystals of tellurium oxide have been optimized.

The array of 20 bolometers of 3x3x6 cm3 has been dismounted and re-mounted after lapping the crystals, and cleaning all the copper frames. A neutron shield of borated polyethylene has been mounted around the set-up. As a consequence the background in the energy region of neutrinoless double beta decay has been reduced by a factor of two.

R&D has been carried out in Hall C. New lapping and polishing procedures were adopted for the crystals of 5x5x5 cm3 to be used in CUORICINO (and hopefully in CUORE) in order to reduce the surface activity. This procedure is going on in the Insubria University in Como. A new set-up for 4 of these crystals, with new suspensions such to decrease microphonics has been constructed and has already employed.

At the end of 2001 ten crystals have been lapped and four of them have been mounted in the dilution refrigerator in Hall C.

The following achievements have been obtained:

Stop of 20 crystal array detector measurement. New limits on 2-neutrinos and neutrinoless double beta decay. Remounting of 20 crystal array detector after lapping and polishing of all | 31-01-2001 | 100%
Stop of 20 crystal array detector experiment. Mounting of CUORICINO | 31-10-2001 | 50%

Milestones 2002

Mounting of CUORICINO | 31-03-2002
Conclusion of a first series of measurements on the neutrinoless double beta decay. New limit on interactions of WIMPS and first limit on interactions of solar axions. | 31-12-2002
Preparation of a detailed design for CUORE | 31-03-2002
R&D in hall C to improve energy resolution and radioactive background. Study of new types of framing and suspensions Study of new crystals | 31-12-2002

3. INFN contribution to the experiment in terms of manpower and financial support

- Manpower: 15 researchers (6.4 FTE), 4 technicians (2 FTE)
- Budget for the year 2002: 175 kEuro

4. Publications in refereed journals (in 2001): 2

5. Conference talks (in 2001): 5

6. Number of undergraduate and doctoral thesis on the experiment:

n.1 Ph.D.;

n.3 Laurea diplomas

7. Leadership role and primary responsibilities of the experiment

E.Fiorini (Mi) is the spokesman of the experiment.

Milano Group is responsible of the cryogenic activity and of the measurement of the radioactive background;

Milano group is the only one involved in development of data acquisition and electronic read-out for arrays of cryogenic detectors

8.Innovative instruments:

As mentioned before the presently operating array is by large the most massive ultra-cryogenic set-up in the world

The alpha particle resolution obtained with the large crystal of tellurides is the best of the ones obtained with any type of detector

9.Competing experiments

There are only four other groups so far operating massive detectors underground and none of them searches for beta decay

The Milano group is the only one to perform gamma spectroscopy at high energy and alpha spectroscopy with thermal detectors

10.International committee which has reviewed the experiment

CUORICINO, the first phase of CUORE experiment, is annually reviewed by the INFN National Committee II.

The status of CUORICINO has been reported and approved in September by the International Scientific Committee of the Gran Sasso Underground Laboratory and by the funding authorities of INFN and DOE (for the Berkeley group)