Report notes about Bi207 source to the CALCI meeting

1. There is a common understanding that the Bi207 source is a state-of-the-art and stable calibration system
   easy to install in protoDUNE

2. A source test campaign, realised in a 50 liters cryostat in 2022, showed the identification of a clear decay peak (1 MeV),
   and a strategy to background assessment from nearby decay energies.
   Although this campaign was made with a 3KBq source, a high activity source (37 KBq) was bought by CERN group and new campaign
   is about to be done using both sources.

3. The readout plane of the 50 liters dewar consists on three strip planes: two induction planes (40 strips every one, 7.5 mm pitch) followed
   by a colection plane with 48 strips and 5 mm pitch.
   The 128 channels are read by a front-end boad card (FEMB) similar (?) to the ones being used on protoDUNE acquisition. 

3. Two Bi sources will be further installed (before summer) in protoDUNE.
   That will require optimally to choose places able to detect drifting charges on electronic channels from same FEMB card.
   Discussions are taken place at cern involving M. Fani and DAQ people.

4. At the moment, LIP and Los Alamos groups showed interested to be involved on the Bi source activity.
   In the week after the January's 2023 DUNE general meeting at CERN we had a meeting with Francesco Pietropaolo
   (J. Maneira, F. Barao, W. Campanelli from LIP and M. Fani from Los Alamos) and we also met DAQ people from CERN.
   At LIP, we are currently developing a C++ framework to re-analyse the data from 2022 campaign.
   This involves, binary data reading, developing analysis estimators to tag source and muon events.

   
F Barao
April 12, 2023