A large number of rooms have been reserved in the Villa Mercede Hotel at the rate of 70 EUR per night, including breakfast and transportation to the course venue (LNF, about 1.5 km away). In case you are interested in this solution, you must personally contact the hotel (firstname.lastname@example.org) by Oct 15, mentioning the booking code FLUKA meeting. Note that presently you may get a lower rate by booking through the hotel website without any code.
Many other options can be found in Frascati, whose center is about 2 km from the LNF.
Another possibility is to stay in Rome and commute by train: the Tor Vergata station (not the Frascati one) is very close to the LNF and the journey from/to the Rome main station (Roma Termini) lasts about 20 min.