Bicocca, 20 Marzo 2008 1

Summary of the job made so far that has nothing to do with the fSummary of the job made so far that has nothing to do with the frontront--end end …… (1)(1)

A great fraction of our time, not foreseen in advance, was spent for the development of the cryogenic set-up not directly connected to the first cold stage of amplification.

Many boards has been developed starting from the detector ceramic, the cold resistor board the µ-bridge adapters the cable adapters at 300 K and at cryogenic temperature. All this job was made trying to be synchronized to the mechanical evolution of the project (David), to avoid to add delay.

Bicocca, 20 Marzo 2008 2

Summary of the job made so far that has nothing to do with the fSummary of the job made so far that has nothing to do with the frontront--end end …… (2)(2)

Support was also given to the constructions of the movement of the source shield.

Bicocca, 20 Marzo 2008 3

Summary of the job made so far that has nothing to do with the fSummary of the job made so far that has nothing to do with the frontront--end end …… (3)(3)

Finally we have also taken care of the galvanic separation of the diagnostic of the fridge to suppress EMI and ground loop with a set-up that will be managed from the acquisition system with optical fibers link.

Bicocca, 20 Marzo 2008 4

Now we come at the FrontNow we come at the Front--end end …… (1)(1)The job started long time ago.

The first aim was to select JFET transistor able to guarantees very low noise at cold, to match bolometers operated at high temperatures in order to have fast speed of response for minimizing the pile-up.

To characterize many different technologies we designed and built a special automatic set-up able to work 24-hour-per-day, 7-day-per-week.

Bicocca, 20 Marzo 2008 5

Now we come at the FrontNow we come at the Front--end end …… (2)(2)

We succeed in selecting a good process.

From the JFET production we tested every transistor at the operating point and select the 80 for the first phase of MARE.

Bicocca, 20 Marzo 2008 6

Now we come at the FrontNow we come at the Front--end end …… (3)(3)

The cryogenic front-end stage has low noise and a voltage gain of 1 V/V.

This asks to the second stage operated at room temperature to show a much smaller noise than that of the first stage. We have developed this front-end stage with a new configuration and circuit solutions.

The final layout of this second stage is in preparation.

One paper has been already published describing the second stage. A second paper will be submitted soon describing the circuit solution.

An Amplifier for Bolometric Detectors (part II) Claudio Arnaboldi and Gianluigi Pessina

Bicocca, 20 Marzo 2008 7

Now we come at the FrontNow we come at the Front--end end …… (4)(4)

Following the second stage we have the programmable amplifying stage that was already prototyped.

The detector biasing was also designed and prototyped.

Both the second stage and the biasing network final layout are under development.

Bicocca, 20 Marzo 2008 8

Now we come at the FrontNow we come at the Front--end end …… (5)(5)

We have the antialiasing filter and the trigger-amplifier and their back-planes..

Finally the adapters to the DAQ signal inputs..

Some boards are ready and some other are in the population phase.

Bicocca, 20 Marzo 2008 9

Now we come at the FrontNow we come at the Front--end end …… (6)(6)

The cabling from the front-end to the DAQ is under the assembling phase.

Bicocca, 20 Marzo 2008 10

Time schedule (1)Time schedule (1)

We think (and hope) to finish the job within the end of the summer.

Why a so long delay?.....

Bicocca, 20 Marzo 2008 11

Time schedule (2)Time schedule (2)

There are many different causes, con-causes, that determine the delay.

We did not considered to design the many items for the construction of the cold set-up, not directly connected with the front-end;

From the beginning of 2007 the contribution from Giulio to our activity drop-out from 100 % to 0 % at the end of July;

From the 10 of January 2007 up to now the (official) support from Claudio drop out from 100 % to 40 % (fortunately Claudio was and is not so fiscal, giving anyway a contribution that range between 60 % to 70 %).

Bicocca, 20 Marzo 2008 12

Financial (1)Financial (1)

To complete the front-end we estimate the need for 20 K€ to be spend from now.

Bicocca, 20 Marzo 2008 13

Financial (2)Financial (2)

The indicated cost is not extra.

It was a fault of Gianluigi that misunderstand a mail from Angelo the past year.

The result was that the 20 K€ were not asked to INFN within the proper time.