sPHENIX HCal discussion

[woody <woody AT bnl.gov>]

Hi John^2,
  I've heard about such effects before but I must say I don't understand the mechanism for it. Kurtis Johnson mentions it in the Particle Data Book but says that "the data are sketchy and mechanisms not understood". I have to admit, it's not something you hear about a lot, but that's not to say there isn't some possible effect due to the magnetic field. He also says that not all types of scintillators are affected, so maybe ours isn't. I don't know whether the magnet over in Instrumentation is still up and running but I guess maybe we should check ours.

Cheers,
Craig

On 10/24/2016 2:48 PM, John Lajoie wrote:

Hi John,

    Wow, I wouldn't have thought that would be a significant effect!

    We have a number of things that are all pointing towards more light - new tiles, magnetic field effect. It's a good situation to be in, I suppose, but this is all going to complicate getting the gains right to avoid saturation.

John

On 10/24/2016 12:30 PM, John Haggerty wrote:

Thanks again to John Lajoie for organizing the weekend get-away to Ames.

There was one other thing I meant to move from my notebook to the 
record, which has to do with the effect of magnetic field on 
scintillator.  There are other references out there, but this is a good 
starting point:

Maurizio Bertoldi, Daniel R. Green, Vasken Hagopian, John Marraffino, 
Anatoly Ronzhin, James Thomaston, Scintillators in magnetic fields up to 
20 T, Nuclear Instruments and Methods in Physics Research Section A: 
Accelerators, Spectrometers, Detectors and Associated Equipment, Volume 
386, Issue 2, 1997, Pages 301-306, ISSN 0168-9002, 
http://dx.doi.org/10.1016/S0168-9002(96)01178-3.
(http://www.sciencedirect.com/science/article/pii/S0168900296011783)

Abstract: Plastic scintillators and wavelength shifting fibers have been 
placed in magnetic fields of up to 20 T and the change in light yield 
measured. The light yield in scintillators increases at very low 
magnetic fields and continues to increase with increasing field until 
saturation at about 2 T. The maximum increase is between 6% and 8%, 
depending on the plastic composition. This increase is due to the 
polymer and not due to the dyes (fluors) used in the scintillators. No 
change of light yield due to magnetic fields has been observed in 
wavelength shifting fibers.

There's a magnet in Instrumentation that I think we could use to see 
what the effect on our tiles is so we know what to expect.

--

John Lajoie

Professor of Physics

Iowa State University

 

(515) 294-6952

lajoie AT iastate.edu

Contact me: john.lajoie

_______________________________________________
Sphenix-hcal-l mailing list
Sphenix-hcal-l AT lists.bnl.gov
https://lists.bnl.gov/mailman/listinfo/sphenix-hcal-l