Author/Authors :
Avvakumov، نويسنده , , S. and Barrett، نويسنده , , W.L. and Belias، نويسنده , , T. and Bower، نويسنده , , Robert C. and Erwin، نويسنده , , A. and Kordosky، نويسنده , , M. and Lang، نويسنده , , K. and Lee، نويسنده , , R. and Liu، نويسنده , , J. and Miller، نويسنده , , W. and Mualem، نويسنده , , Gayle L. and Nichol، نويسنده , , R. and Nelson، نويسنده , , J. and Pearce، نويسنده , , G. and Proga، نويسنده , , M. and Rebel، نويسنده , , B. and Ruddick، نويسنده , , K. and Smi، نويسنده ,
Abstract :
We report on the observation and measurements of unexpected background rates in the MINOS Far Detector. The noise level at the Far Detector is significantly greater than that expected from natural radioactivity and intrinsic photomultiplier dark current. We have conducted a series of additional tests which demonstrate that the excess rate is caused by spontaneous light emission in the wavelength-shifting fibers, which are used to read out signals from scintillator strips. This noise due to fibers exhibits an exponential fall off with time with a decay time constant of the order of 100 days.
Keywords :
Fibers , Photomultipliers , Scintillator readout , Fiber readout , Dark noise , Wavelength-shifting fibers
