MANU2

Collaboration:

INFN and University of Genova, LNF

Location of the experiment: Genova

National Responsible: F. Gatti (Ge)

Home page of the Experiment:

1. Goal of the experiment.

The experiment aims to perform the total energy disperse beta-spectroscopy of 187Re by means of cryogenic micro-calorimeters working at 100 mK, with an energy resolution competitive to the electron-impulse beta spectroscopy of the Tritium experiments. Check of the anomalies at the end-point and a model independent measurement of neutrino mass are the main physics goals. Behind the aims, the study of the Beta Environmental Fine Structure for application to the matter science is of primary interest.

More on the experiment...

2.

Activities during 2002

The experiment needs micro-calorimetric detectors with a target resolution (FWHM) of 5 eV and a broad band SQUID-readout. In the detector’s R&D, we achieved a resolution a factor 3 from the target (about 85% of the Milestone of 2001). In building more channels of the electronics, which is based on commercially available new SQUID-arrays by Hypress (USA), we encountered a huge amount of problems caused by inadmissible performances of several SQUID chips. Defects as excess noise, kinks in the characteristics, biasing problems, persuaded us that the SQUID-array technology, commercially available, is unsuitable for building a large number of channels with a long lifetime as needed for MANU-2. Furthermore, Hypress didn’t support our effort in selecting the best chips. Due to these external causes, in agreement with the referees and the Scientific Committee, the previous milestones 2002 have been changed and the budget for the electronic construction has been frozen-out. New milestones has been fixed, which require an investigation for an equivalent SQUID device and a study of the applicability of the transformer-JFET amplifier. Provisional results are: 1) found a SQUID of conventional technology; 2) completed the study of low temperature transformer and the design of 1pA/sqrt(Hz) current noise transformer-JFET amplifier.

An important activity was started and successfully done in 2002: a test experiment at the synchrotron light at ESRF-Grenoble in which we used for the first time in Italy (3rd in world after 2 experiments done with STJ detectors) the microcalorimeters as X-ray spectrometers. We improved the X-ray resolution of the ESRF GILDA beam-line by a factor 3, only limited by the huge environmental noise.

As a summary the following achievements have been obtained:

- Search for a new SQUID to be tested for the experiment (100%)
- Design of the transformer-JFET amplifier (80%)
- Test experiment at ESRF for microcalorimetric X-ray spectrometer (100%)

Milestones 2003:

Finalization of the front-end electronics (SQUID or Transformer-JFET in AC) | 31-05-2003
Completion of the measurements on each prototype with the current electronics | 30-06-2003
Completion of the experimental set-up and start data taking | 30-11-2002

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

Manpower: 13 researchers (6.2 FTE), 2 technician (1.3 FTE) and support from the mechanics and the electronics workshops of INFN-Genova

Budget for the year 2002: 0.6% of the CSN2 budget for 2003

4. Publications in refereed journals (in 2001):

5. Number of conference talks (in 2001): 1

6. Number of undergraduate and doctoral thesis:

2 undergraduates

7. Leadership role in the experiment.

F. Gatti is the spokesman

8. Innovative instruments

The experiment developed unique thermal detectors with superconducting absorber with high Z (=75) and high density (=21) capable to reach energy resolution about 1 order of magnitude better than commonly available solid-state detectors. Applications to X-ray spectroscopy are under course: first test as X-ray detector at the synchrotron light (ESRF, July 2002) and study for X-ray instruments in space mission for Astronomy. We have successfully examined the perspective of possible application of the BEFS effect for the study of microcrystalline structure in situations where EXAFS is not suited. An experiment for detecting the H position in solids is planned.

9. Competing experiments

No other groups developed superconducting rhenium detector. No other groups have achieved the sensitivity to observe the beta environmental fine structure of beta decay (BEFS). Our group first proposed the use of Rhenium for neutrino mass measurements, and observed for the first time the beta spectrum with cryogenic detectors. The competing experiment is Mi-Beta that started the data taking after MANU was completed. Mi-Beta makes use of absorber made of dielectric crystal of silver perrhenate. The resolution of Mi-Beta is better than our old detectors, with equivalent or lower mass of rhenium-187. Presently, MANU-2 is developing detectors with same performances. Better performances are predicted in the near future.

10. International committee which has reviewed the experiment

The INFN National Committee II annually reviews MANU2.