Mi-Beta
Collaboration:
Location of the experiment: LASA (Mi) for cryogenic measurements and Milano-Bicocca for Radioactivity Measurements, IRST of Trento for the preparation of Silicon implanted thermistors.
National Responsible: E. Fiorini (Mi)
1. Goal of the experiment
Development of microbolometers for high resolution measurement of X-rays and construction of an array with at least ten absorbers of Silver Perrhenate to investigate the beta decay spectrum of 187Re in view of the measurement of neutrino mass.
2.
Activities during 2002
An
array of 10 crystals is running since June in the old cryostat (the
new one , even if tested -see later- has poorer operating conditions).
A paper with the first bolometric limit on electron antineutrino
mass and with the best world measurement of the transition energy
and half lifetime of Re-187 has been submitted to
Phys.Rev.Lett.
The
new cryostat has been mounted in the new laboratory of Milano-Bicocca.
It has reached a record value for the base temperature (~6mK).
The operating conditions of the Laboratory have however not
yet beem optimized yet
Some
properties of the micromachining (heat conductance of the "legs", and
reproductibility of the Si:P sensors) have been studied
New detectors have been prepared at the beginning of 2002 and mounted in the presently running array
The following achievements have been obtained:
(*) the measurement is still in progress from June 2002
(**) this operation will be posponed after the end of the present measurement
(***)The Milano-Bicocca Cryo-laboratory is not yet ready
Milestones 2003:
Final
measurement of the limit on the neutrino mass after a
year of data taking with the 10 microbolometer array |
30-06-2003 |
Study
of the internal calibration of a bolometer for the
measurement of beta decay |
31-01-2003 |
Final
decision on the participation to the KATRIN experiment or
on the implementation of an array of 10 microbolometers
of Rhenium compounds. |
31-10-2003 |
3. INFN contribution to the experiment in terms of manpower and financial support
Manpower: 13 researchers (5.1 FTE), 5 technicians (2.3 FTE)
Budget for the year 2003: 0.7 % of the CSNII budget
4. Publications in refereed journals (in 2002): 3
5. Number of conference talks (in 2002): 1
6. Number of undergraduate and doctoral thesis on the experiment:
n.1 Laura diplomas
7. Leadership role and primary responsibilities of the experiment
E. Fiorini (Mi) is the spokesman of the experiment and the leader of the contacts with the Berkeley and Trento groups;
Milano is the coordinating group of the European Network for Cryogenic detectors.
7. Innovative instruments:
The results on X-ray spectroscopy are among the best in the literature
The Genoa and Milano groups are the only ones to perform, with different cryogenic techniques, a calorimetric measurement on the neutrino mass
Application of the technique of microbolometers in Material Science and Astroparticle Physics is being pursued
8. Competing experiments
There are only four groups so far that can compete with Milano in X-ray spectroscopy, and only one uses a similar technique
For the Rhenium experiment the Milano group is proud to compete with an highly scientific and technically qualified group like the Genoa one
9. International committee which has reviewed the experiment
The INFN annually reviews Mi-Beta.
The experiment has been reported to three meeting of the CEE TMR and successfully reviewed by the European panel. A new network on Cryogenic Detectors has been recently approved in the frame of the TMR activities