gold-plated protons!!

From: John Calarco (jrc@einstein.unh.edu)
Date: Sun Jul 21 2002 - 11:10:04 EDT


While playing around with Chris' run 741, the one with 5 SCCM of gas flow,
I noticed that RTOF11 displays a prominent broad peak well above the one
corresponding to minimum ionizing particles. Of course RTOF11 bottom has
been giving suspicious TDCs with lots of extra noise in them. So I wanted
to investigate what was real and what was noise.

So I have placed a cut around the the broad ADC peak and looked at various
histograms. Attached are files showing the ADC spectra of all right bottom
ADCs, of RTOF11 top ADC which shows a similar broad peak, and of various
combinations of LTOF mean time (mt) vs RTOF11 mt. These include the uncut
version of LTOF3 mt vs RTOF11 mt as well as LTOF2 - 7 mt vs RTOF11 mt each
cut on the broad ADC peak.

The results are very interesting. As you can see, the cut on ADC
eliminates most of the noise in the LTOF3 mt vs RTOF11 mt as expected if
there is a noisy cable problem into the RTOF11 TDC. It leaves the same
mt vs mt peak that was noted in my earlier BlastTalk communication about
e-p coincidences. Furthermore this peak is strongly correlated in LTOF3 -
6 but missing as you got LTOF2 at low angles anf LTOF7 at larger angles.

So why is this broad peak so prominent in RTOF11 ADCs and not others? I
think the answer is in Adrian's energy deposition simulation which he
posted to BlastTalk about a week ago. It is at right around this angle
that the proton recoils from e-p reach their maximum energy deposition
from the Bragg curve ... i.e. they're ranging out in the TOFs at this
angle.

Comments??

-- 
John R. Calarco
Dept. of Physics
Univ. of New Hampshire
Durham, NH 03824
phone: (603)862-2088
FAX:   (603)862-2998
email: calarco@unh.edu












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