Calibration sources for CYGNO
Flavio Di Clemente
Giulia D’Imperio
Gianluca Cavoto
9 / 3 / 20
964 keV
1120 keV
Problem: track containment
In general, only a fraction of the total energy carried by the particle is deposited inside the sensitive region
The maximum registered energy contained inside a 0.5m3 region (between cathode and readout) is ~420keV
Compton edges
Electrons from 60Co decays
Initial electron energy [keV]
Fraction of deposited energy [keV]
60Co
55Fe
Low energy X-rays can deposit all of their energy
55Fe
We have a factor ~50 between the # of tracks in the side camera (in which the source is) and the # of tracks in the center camera.
How can we move the source?
Can we swap cameras positions?
A “double-side” calibration would decrease the ratio by a factor 2
Problem: coverage area
it is possible to carry out a systematic study of the detector response to the various isotopes suitable for our needs.
How our calibration source should be made
This is required to have tracks fully contained in the sensitive region, especially for side-cameras
The crucial point of the double-sided calibration is being able to calibrate the cameras in the center
To make it simple to build the calibrated emission spectrum of the source
Preview*
*A full study will be available very soon!
125 I (Half-life: 60d)
The energy range of fully-contained tracks is much wider than the 55Fe case
The spectrum offer different, well separated, energy regions
Is the half-life too low?
(it depends on how much time the calibration scan will take)
The ability to cover many cameras is not that better with respect to the case of the 55Fe
133Ba (Half-life: 10.5y)
The energy range of fully-contained tracks is even wider than the 125I53 case
Unfortunately the 133Ba introduces higher levels which contribute only to noise, since they are usually partial tracks
Even for 133Ba56, the cameras coverage is not that better with respect to the case of the 55Fe
There are many other nuclides to be tested!
Recap
We still haven’t figured out how to solve the coverage problem. Nevertheless we found other suitable choices for our sources, which can improve our energy range in the calibration scan.
Full track containment and coverage are opponents, so we should find the balance between this two features.
A double-sided study will be done, and some numbers on activities will be therefore carried out soon.