Yesterday we improved NaI spectra by checking them one by one with lead blocks stacked as a housing. Though the threshold levels of CFDs were few mV or less than 20mV and a bias of NaI7 might be high (~1500V), the shapes of spectra looked OK. Now 511keV peaks are around 1500ch in every sprctra.

## To-do list for NaI detectors ##

1.Check efficiency and calibrate NaI by using Na22 source and Cs137. Basically the interest of region is around 511keV and we need precise information up to 1MeV so that Na22 and Cs137 are enough to calibrate.a

2.Align NaIs on F3 chamber after the other F3 works done. I'm thinking of an arrangement of the NaIs array like, for instance, NaI7 should be put outside, and relatively good NaIs should be at center.

3.After setting them on a bucket, check efficiencies again. For testing positional dependenices, we should do it from several different positions.

4.Determine the threshold level of CFDs so as not to make DAQ busy. (It can be solved by using divider?)