I removed the term "- cal.length/cal.Vsc" from the calculation of "time"
in TBLDetHit.cc which accounts for the light traveling time in a
scintillator, since it is already incorporated in the offsets from
blast.sc_cal. The offsets in blast.sc_cal have been determined from
flasher data without explicitly excluding the above term (refer to PK's
macro tof_tdc_offsets.C).
The ntuple entry "time" will thus shift by L/v. For the 180cm long ToFs,
this is about 6ns, for the 120cm ToFs about 4ns.
For physical particle flight times only the differences like "ttl-ttr"
matter; i.e. for ToF(180cm)-ToF(180cm) differences nothing will change,
however longToF-shortToF differences will move by about 2ns! This might
requiree revisions of cut conditions, e.g. e-d elastic identification ...
While this effect is small for ToF-ToF coincidences, it is rather big
for ToF-Ohiowall coincs (a shift of more than 20 ns)
So far, I have only checked it into cvs, blast account (and crunching) is
not yet updated.
MK
--+-------------------------------------+--------------------------+ | Office: | Home: | |-------------------------------------|--------------------------| | Dr. Michael Kohl | Michael Kohl | | Laboratory for Nuclear Science | 5 Ibbetson Street | | MIT-Bates Linear Accelerator Center | Somerville, MA 02143 | | Middleton, MA 01949 | U.S.A. | | U.S.A. | | | - - - - - - - - - - - - | - - - - - - - - -| | Email: kohlm@mit.edu | K.Michael.Kohl@gmx.de | | Work: +1-617-253-9207 | Home: +1-617-629-3147 | | Fax: +1-617-253-9599 | Mobile: +1-978-580-4190 | | http://blast.lns.mit.edu | | +-------------------------------------+--------------------------+
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