Re: [BLAST_ANAWARE] Cosmics Field and No Field, 3288 and 3310... poor results...

From: Eugene J. Geis (Eugene.Geis@asu.edu)
Date: Thu Nov 13 2003 - 16:00:33 EST


Hi Karen,

> d) That spike in L1, L2 and R1 (no field) looks to be in about the
>
> right spot for the pedestal. If you plot those ADC channels without
> the
> cut on the corresponding TDC, is the pedestal spike in the same
> location? But cutting on the TDC should show you which box actually had
> a
> signal larger than the discriminator threshold. Try cutting on atl<4095
>
> (full-scale on the TDC) as well as atl>0, or at least plot the TDC, or
> TDC
> vs ADC, to see what is going on.

I checked on all of these. The TDC's in the Cherenkov fall in the exact same
place as all the other events within the spectra. The corresponding
scintillator's ADC's also have the exact same signature as the rest of the
spectra. There is one strange thing I've found. In the scintillators, the
spectra for the majority of the cherenkov ADC's is a rising curve up to about
channel 2900. After that, there is a huge drop and a few events that land above
2900. These give a strange peak in the Cherenkov ADC's that fall at exactly
channel 950. This doesn't correspond to the pedestal on the scintillator
though...?
   I've attached a postscript of L1 analysis. Upper left hand is the total ADC
spectra. Upper Right is the scintillator TDC of the left side when CC_L1 is
hitting. Left middle is a cut made on the Cherenkov adc and the consequent
scintillator TDC next to it. On the lower left is the Cherenkov ADC when I make
the cut on the scintillator TDC being greater than 2985. The CC_L2 and CC_R1
show similar behavior...

> a) To figure out R0 and R2 with no field, someone needs to look
> with a
> scope at the signal going to the ADC, be sure there is no DC offset (
> you
> won't do that from Arizona, of course). I don't know why the offset
> would
> go away with the field on, though. Probably worth plotting the TDCs for
>
> these, also.

The one thing worth noting about these two CC's is that the TDC peak falls at
about channel 3350 where the tdc's for those CC's that have reliable spectra are
all hitting at about Channel 4000. That is all I can say. The scintillators
give no hint as to what might have happened.

> b) As for the Left side practically disappearing when the field is
>
> turned on -- the trigger hardware has been changed to OR the Cerenkovs
>
> before the MLU. I installed the cable for the left on Monday (11/10),
>
> which I believe is AFTER your no-field run, BEFORE the field run. So I
>
> will go and check the cable again.
> c) Maybe R1 signal doesn't attenuate as much as R0, R2 with the
> field
> on, so more events pass the discriminator.
>

Sounds like that was the problem with those. Thanks for the help. Almost all
questions answered! Woohoo!

Eugene

 
>
> At 01:45 AM 11/13/2003 -0700, Eugene J. Geis wrote:
>
> >Hello,
> >
> > >
> > > You need to explain what these plots are. I, for one, cannot read
> the
> > > sub-microscopic print in the title box. And while ROOT allows you
> to
> > > expand that box, gv does so only at the expense of not being able
> to
> > > see
> > > the rest of the plot.
> >
> >I apologize for my inability to be specific,
> >
> >When I sent the postscripts, I wrote:
> >"I have crunched the two cosmic runs and plotted the adc's in the
> Cherenkovs."
> >These two cosmic runs are 3288 (no field) and 3310 (full field)
> >
> >repeating verbatim:
> >I have 'plotted the ADC's in the Cherenkovs.' Cosmic.ps is full field,
> and
> >Cosmic_no_Field.ps is self-explanatory. I, for one, do not know how to
> open
> >postscripts in ROOT... I only use gv and the zoom works fine for me.
> To
> >be more
> >specific about the layout:
> >
> >----------------------------------------------------
> >| | |
> >| ADC of Cher | ADC of Cher |
> >| L-0 | R-0 |
> >| | |
> >|---------------------------------------------------
> >| | |
> >| ADC of Cher | ADC of Cher |
> >| L-1 | R-1 |
> >| | |
> >|---------------------------------------------------
> >| | |
> >| ADC of Cher | ADC of Cher |
> >| L-2 | R-2 |
> >| | |
> >|---------------------------------------------------
> >
> >This is the layout of the plots. Note that all of the events in the
> upper and
> >lower right-hand spectra are pedestals and NONE of the events were
> recorded
> >where the "real" spectra 'should' be. When field is off, the "real"
> spectra
> >would actually fall through ~channel 4000. This can be seen in the
> left-hand
> >side, otherwise known as CC L0, CC L1, and CC L2. It is also apparent
> in
> >CC R1
> >which is the right-hand middle plot. Notice in the second file,
> otherwise
> >known
> >as Cosmic.ps (with full field on), that all signature of the typical
> ADC
> >spectra
> >disappears and now we find that CC R0 and CC R2 (the upper and lower
> >right-hand
> >plots) have reappeared in all their fine splendor. The only conclusion
>
> >that can
> >confidently be drawn is the comparison of CC R1_No_Field with CC
> R1_Full_Field
> >where we notice that there is a severe change in width when the field
> is
> >on. We
> >also notice when calculating efficiencies from previous H2 runs with no
> field
> >that the respective Cherenkov efficiency for R1 falls by ~35% when
> field
> >is on.
> > We have nearly 100% efficiency with field off. Cosmics will give a
> greater
> >proof of this change in the ADC spectra once it is consistently
> measured twice
> >with field on and then field off... That means, to be more specific,
> all
> >ADCs of
> >all Cherenkovs firing consistently. Until then, I still have these
> questions
> >about these Cosmic runs and ONLY these Cosmic runs...
> >
> >a. I have no idea why R0 and R2 look the way they do with No field...
> There
> >should be "real" spectra, not just pedestals...
> >
> >b. Why did the left side barely fire at all with field on?? Is it
> >something with
> >the trigger???
> >
> >c. Why does R1 have such an asymmetric number of hits when compared to
> R0 and
> >R2, namely, 310k events as compared to 57k and 70k, never mind the
> petite
> >hundreds of events in the left CC's?
> >
> >d. What is that strange peak in the ADC of L1, L2, and R1 in the no
> >field postscript? We do not understand what this peak may be.
> >
> >Thanks for the love,
> >eugene
> >
> >
> >
> >--------------------------------------------------------------------------
> >Eugene Geis
> >PhD Student, Physics Department, ASU
> >Research Affiliate, MIT-Bates Laboratory of Nuclear Science
> >eugene.geis@asu.edu
> >--------------------------------------------------------------------------
> >-------------------------------water is
> good------------------------------
> >--------------------------------------------------------------------------
> >** Check Out the Phatty Acidz @ www.phattyacidz.com **
>
>

--------------------------------------------------------------------------
Eugene Geis
PhD Student, Physics Department, ASU
Research Affiliate, MIT-Bates Laboratory of Nuclear Science
eugene.geis@asu.edu
--------------------------------------------------------------------------
-------------------------------water is good------------------------------
--------------------------------------------------------------------------
** Check Out the Phatty Acidz @ www.phattyacidz.com **





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