Cerenkovs in the vacuum?
- it will make the gas filling very difficult
- if anything breaks (SiPM/LED) it will give us a hard time to exchange something.
- in case we lose some Gas this would have more dire consequences than it would if the detector would sit by itself in air.

Hybrid setup?
- the case where the Cerenkovs are placed further back, behind a longer vacuum chamber is OK.
- this would give us the benefit of less multiple scattering, better resolution (because of the larger separation of particles after the magnet) without so much headache with having the Detector *inside* the vacuum chamber.