[G8b_run] Fwd: g8b TOF paddle issue
Eugene Pasyuk
pasyuk at jlab.org
Tue Mar 19 16:36:38 EDT 2013
----- Forwarded Message -----
From: "Eugene Pasyuk" <pasyuk at jlab.org>
To: "Michael Dugger" <dugger at jlab.org>
Cc: "Ken Livingston" <Kenneth.Livingston at glasgow.ac.uk>, "Franz Klein" <fklein at jlab.org>, "Brian Vernarsky" <soulish at gmail.com>, "Volker Crede" <crede at fsu.edu>, "Patrick Collins" <pcollins at jlab.org>, "Charles Hanretty" <hanretty at jlab.org>
Sent: Tuesday, March 19, 2013 4:21:10 PM
Subject: Re: g8b TOF paddle issue
Let's have a meeting. I set up doodle: http://doodle.com/ycqshd8fpnda66mx
-Eugene
----- Original Message -----
> From: "Michael Dugger" <dugger at jlab.org>
> To: "Volker Crede" <crede at fsu.edu>
> Cc: "Ken Livingston" <Kenneth.Livingston at glasgow.ac.uk>, "Franz Klein" <fklein at jlab.org>, "Brian Vernarsky"
> <soulish at gmail.com>, "Eugene Pasyuk" <pasyuk at jlab.org>
> Sent: Tuesday, March 19, 2013 3:36:51 PM
> Subject: Re: g8b TOF paddle issue
>
>
> Hi,
>
> This could be scary.
>
> From what I understand, this problem will create phi dependent
> inefficiencies. This will especially true for single track events.
> However,
> if an analysis uses the data to self analyze the phi dependent
> efficiencies (e.g. forming quantities like (Y_PARA - Y_PERP)/(Y_PARA
> +
> Y_PERP)), then the recooking of data will only help add statistics
> for
> those type of analyses.
>
> Since I have two channels of g8b that have gone through analysis
> review,
> and Volker is either finished with analysis review, or nearly so, it
> is
> important that we determine if those analysis can remain as is.
>
> If it is determined that all of the analyses must use recooked data,
> we
> need to do the recooking as soon as possible.
>
> Take care,
> Michael
>
> On Tue, 19 Mar 2013, Volker Crede wrote:
>
> > Hi all,
> >
> > It sounds really scary. Yes, we should meet and discuss this.
> >
> > Volker
> >
> >
> > On Mar 19, 2013, at 12:34 PM, Michael Dugger <dugger at jlab.org>
> > wrote:
> >
> >> Hi,
> >>
> >> Having a meeting makes sense.
> >>
> >> Take care,
> >> Michael
> >>
> >> On Tue, 19 Mar 2013, Ken Livingston wrote:
> >>
> >>> Hi All,
> >>> It does indeed look like we cooked with the version that was in
> >>> /home/clasg8/g8/packages/
> >>> where, as Brian says, we had
> >>> #define SC_TDC_MAX 4096
> >>>
> >>> if I look at set_env_g8b.sh see
> >>> export CLAS_PACK=/u/home/${RUN_USER}/g8/packages
> >>>
> >>> I think we do need to consider recalibrating the TOF and
> >>> recooking the data. At least starting with one coherent peak
> >>> setting.
> >>>
> >>> What do you all think?
> >>> We should at least have a meeting to discuss this.
> >>>
> >>> Cheers,
> >>> Ken
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> On 19/03/13 13:43, Franz Klein wrote:
> >>>> sorry, replied only to Eugene ...
> >>>> ----- Forwarded Message -----
> >>>> From: "Franz Klein" <fklein at jlab.org>
> >>>> To: "Eugene Pasyuk" <pasyuk at jlab.org>
> >>>> Sent: Tuesday, March 19, 2013 9:38:42 AM
> >>>> Subject: Re: g8b TOF paddle issue
> >>>> Yes, Eugene, I worked on the copy_pipeline.cc routine in the
> >>>> beginning of g9a ... mostly because the SC, EC banks took the
> >>>> first TDC entry from SCT, ECT instead of the one which is in
> >>>> the 'right' (expected) range.
> >>>> So maybe I'll take a look first into the g8b version of this
> >>>> routine as well as SCT, ECT, REF.
> >>>> ----- Original Message -----
> >>>> From: "Eugene Pasyuk" <pasyuk at jlab.org>
> >>>> To: "Franz Klein" <fklein at jlab.org>
> >>>> Cc: "Michael Dugger" <dugger at jlab.org>, crede at fsu.edu, "Brian
> >>>> Vernarsky" <soulish at gmail.com>, "Kenneth Livingston"
> >>>> <Kenneth.Livingston at glasgow.ac.uk>
> >>>> Sent: Tuesday, March 19, 2013 9:29:45 AM
> >>>> Subject: Re: g8b TOF paddle issue
> >>>> One thing which comes to mind is that at some point after
> >>>> pipeline TDC were installed we discovered that there is some
> >>>> issue in on-line procedure of matching TDC and ADC from SC and
> >>>> SCT banks and remaking of raw SC bank. The procedure was
> >>>> revisited and as I recall we used new matching procedure in
> >>>> user_ana for g9a data. May be this is the reason for g8b
> >>>> problem?
> >>>> -Eugene
> >>>> ----- Original Message -----
> >>>>> From: "Franz Klein" <fklein at jlab.org>
> >>>>> To: "Kenneth Livingston" <Kenneth.Livingston at glasgow.ac.uk>
> >>>>> Cc: "Michael Dugger" <dugger at jlab.org>, "Eugene Pasyuk"
> >>>>> <pasyuk at jlab.org>, crede at fsu.edu, "Brian Vernarsky"
> >>>>> <soulish at gmail.com>
> >>>>> Sent: Tuesday, March 19, 2013 9:23:00 AM
> >>>>> Subject: Re: g8b TOF paddle issue
> >>>>> Ken,
> >>>>> unfortunately I don't remember whether we checked or changed
> >>>>> the cut
> >>>>> on overflows. We took the code from eg3 (Joern) which assumes
> >>>>> TDC
> >>>>> entries in the range ~1000 to ~6000 (depending on particle and
> >>>>> REF
> >>>>> signal).
> >>>>> However, Brian found out quite some time ago that often in
> >>>>> multi-track events many track candidates weren't getting into
> >>>>> time-based tracking due to missing timing information from ST
> >>>>> and/or
> >>>>> SC.
> >>>>> For sure we made the mistake to cut out all SC paddles in the
> >>>>> reconstruction for which the calibration didn't work out
> >>>>> (instead of
> >>>>> letting students worry about SC paddle cuts later in their
> >>>>> analysis). In that sense it might be a good idea to recheck ST
> >>>>> and
> >>>>> SC calibrations and maybe rerun user_ana for some coh.edge
> >>>>> setting
> >>>>> on the farm.
> >>>>> Maybe as a first step, Brian should tar his source code he
> >>>>> copied
> >>>>> from the clasg8 account and we verify whether it is the code
> >>>>> which
> >>>>> was used for g8b reconstruction.
> >>>>> Cheers,
> >>>>> Franz
> >>>>> ----- Original Message -----
> >>>>> From: "Ken Livingston" <Kenneth.Livingston at glasgow.ac.uk>
> >>>>> To: "Brian Vernarsky" <soulish at gmail.com>
> >>>>> Cc: "Michael Dugger" <dugger at jlab.org>, "Eugene Pasyuk"
> >>>>> <pasyuk at jlab.org>, crede at fsu.edu, "Franz Klein"
> >>>>> <fklein at jlab.org>
> >>>>> Sent: Tuesday, March 19, 2013 8:18:45 AM
> >>>>> Subject: Re: g8b TOF paddle issue
> >>>>> Hi Brian,
> >>>>> There's certainly something funny going on there which we need
> >>>>> to get
> >>>>> to
> >>>>> the bottom of.
> >>>>> However, I'm not sure your diagnosis is correct.
> >>>>> As far as I can see, when I log on to the clasg8 account cd
> >>>>> $CLAS_PACK
> >>>>> directory is set to
> >>>>> /home/clasg8/packages, not /home/clasg8/g8/packages/ where you
> >>>>> mention
> >>>>> finding the header file with the old version of sc.h.
> >>>>> In the clasg8 account version of $CLAS_PACK/include/sc.h the
> >>>>> relevant
> >>>>> line is
> >>>>> #define SC_TDC_MAX 8192 /* pipeline */
> >>>>> Do any of the rest of you have any opinion or memory on that?
> >>>>> Regards,
> >>>>> Ken
> >>>>> On 18/03/13 22:03, Brian Vernarsky wrote:
> >>>>>> Hello all,
> >>>>>> In trying to finalize my results for the spin density matrix
> >>>>>> elements
> >>>>>> for the omega I have run into a serious issue with the g8b
> >>>>>> dataset.
> >>>>>> When I project out my spin density matrix elements I found
> >>>>>> that the
> >>>>>> unpolarized elements, which can be compared to previous
> >>>>>> experiments
> >>>>>> (g11a most notably), were slightly offset with respect to
> >>>>>> those
> >>>>>> previous measurements. I have shown these elements at
> >>>>>> previous
> >>>>>> CLAS
> >>>>>> Hadron meetings so some of you may be aware of this.
> >>>>>> I traced the source of my problem back to the fact that the
> >>>>>> phi
> >>>>>> distributions of the particles were skewed and this was not
> >>>>>> properly
> >>>>>> reflected in the monte carlo. Looking further into the issue
> >>>>>> I
> >>>>>> discovered that the start counters have a serious issue with
> >>>>>> detecting
> >>>>>> individual pions; the efficiency varies wildly from paddle to
> >>>>>> paddle.
> >>>>>> However, since we had a one-track trigger and I am looking for
> >>>>>> three-track events with a proton, this was not the source of
> >>>>>> my
> >>>>>> issue,
> >>>>>> however it could be a serious issue for anyone looking into
> >>>>>> single
> >>>>>> pion reactions. The source of my issue is particles that have
> >>>>>> a
> >>>>>> TOF
> >>>>>> paddle set to 0, indicating there is a problem with them. As
> >>>>>> you
> >>>>>> can
> >>>>>> see in the enclosed file phi_distributions_g8b.pdf the actual
> >>>>>> phi
> >>>>>> distribution for each particle (in black) looks to be ok,
> >>>>>> however
> >>>>>> when
> >>>>>> we remove the particles with TOF paddle = 0 (in red) and are
> >>>>>> left
> >>>>>> with
> >>>>>> just the particles with a "good" TOF paddle (in blue) there is
> >>>>>> a
> >>>>>> pretty severe problem, mostly for the pions.
> >>>>>> In looking at the TOF paddle = 0 events for the two pions you
> >>>>>> can
> >>>>>> notice that they are almost the exact same, whereas the proton
> >>>>>> has
> >>>>>> significantly less events with a "bad" TOF paddle. And there
> >>>>>> is a
> >>>>>> definite phi dependence to the bad events. Certainly we
> >>>>>> should
> >>>>>> expect
> >>>>>> some events with bad TOF paddles in every channel, however
> >>>>>> this is
> >>>>>> accounting for almost half of the total events in sector 5 for
> >>>>>> the
> >>>>>> pions. There is no physical reason for this to be so.
> >>>>>> I have found the source of the problem to be in the TDCs of
> >>>>>> the TOF
> >>>>>> paddles. In the file tdcs_and_adcs_g8b.pdf I have shown the
> >>>>>> values
> >>>>>> from the TDCs and ADCs for the TOF paddles, in the order TDCL,
> >>>>>> ADCL,
> >>>>>> TDCR, ADCR, for the proton (top), pi+ (middle) and pi-
> >>>>>> (bottom),
> >>>>>> integrated over all paddles and sectors for one amorphous run
> >>>>>> (48133).
> >>>>>> The blue on each plot are "good" events and the red are
> >>>>>> "bad", or
> >>>>>> TOF
> >>>>>> = 0, events. It is very evident from the TDC plots for all
> >>>>>> particles
> >>>>>> that something turns on at channel 4096. I have tried to
> >>>>>> illustrate
> >>>>>> that by drawing a vertical line at 4096 on the TDC plots. The
> >>>>>> ADC
> >>>>>> plots show nothing out of the ordinary.
> >>>>>> What happened is that before the g8b run the TDCs were changed
> >>>>>> from
> >>>>>> a
> >>>>>> 12-bit system to a 16-bit system, changing the maximum channel
> >>>>>> from
> >>>>>> 4096 to 65536. However, this change was not made in the code
> >>>>>> as in
> >>>>>> the g8b cooking code (found at /home/clasg8/g8/packages/) the
> >>>>>> file
> >>>>>> include/sc.h we find
> >>>>>> #define SC_TDC_MAX 4096
> >>>>>> instead of 8192 like we find in other experiments after the
> >>>>>> TDCs
> >>>>>> were
> >>>>>> changed. (It seems that while we effectively have 65,536
> >>>>>> channels
> >>>>>> in
> >>>>>> practice we only use 8192.) Any particle that registered
> >>>>>> above
> >>>>>> 4096
> >>>>>> on a TDC was deemed a "bad" event in that TDC. If the
> >>>>>> particle had
> >>>>>> a
> >>>>>> "bad" TDCL but a "good" TDCR then it is still possible to
> >>>>>> recover
> >>>>>> the
> >>>>>> events, and vice versa, though not all particles could be
> >>>>>> recovered
> >>>>>> in
> >>>>>> this way. However, if both TDCs measured a value above 4096
> >>>>>> then
> >>>>>> the
> >>>>>> particle was deemed "bad" and assigned TOF paddle = 0.
> >>>>>> For a signifcant number of TOF paddles the range of TDC
> >>>>>> channels
> >>>>>> was
> >>>>>> from 3800-4200, though some skewed higher or lower than
> >>>>>> others.
> >>>>>> For
> >>>>>> paddles where the distribution was quite high as many as half
> >>>>>> of
> >>>>>> the
> >>>>>> pions were cut and a signficant number of protons were also
> >>>>>> cut.
> >>>>>> This
> >>>>>> led to difficulty in calibrating the paddle and so the entire
> >>>>>> paddle
> >>>>>> was cut. There were 31 paddles cut in g8b, more than 10% of
> >>>>>> the
> >>>>>> total
> >>>>>> number of paddles.
> >>>>>> For the pions the cut is pretty evenly distributed across the
> >>>>>> momentum
> >>>>>> spectrum, but for protons it cuts only events above ~550 MeV
> >>>>>> as can
> >>>>>> be
> >>>>>> seen in the file p_dist_bad_paddles.pdf, which shows the
> >>>>>> momentum
> >>>>>> distribution for protons that have been ascribed TOF paddle =
> >>>>>> 0.
> >>>>>> Now,
> >>>>>> this is a small fraction of the total number of proton events,
> >>>>>> but
> >>>>>> it
> >>>>>> is still significant.
> >>>>>> Based on all of this I think that it is imperative that we
> >>>>>> recook
> >>>>>> the
> >>>>>> g8b dataset. We will need to change the value of SC_TDC_MAX
> >>>>>> and
> >>>>>> then
> >>>>>> recalibrate the TOF paddles; hopefully the ones that were
> >>>>>> considered
> >>>>>> "good" before will not need much work, but of the ones
> >>>>>> considered
> >>>>>> "bad" before most of them can almost certainly be salvaged.
> >>>>>> This
> >>>>>> recook is necessary because it is clear that this is
> >>>>>> significantly
> >>>>>> affecting the phi and momentum distributions of all particles
> >>>>>> and
> >>>>>> thus
> >>>>>> will affect all measurements that depend on phi, momentum, TOF
> >>>>>> or
> >>>>>> particle ID. The plus side is that we can recover a large
> >>>>>> number
> >>>>>> of
> >>>>>> paddles and thus increase our statistics significantly,
> >>>>>> especially
> >>>>>> with multi-particle events. Any other minor issues that
> >>>>>> wouldn't
> >>>>>> necessitate a recook on their own can also be addressed before
> >>>>>> we
> >>>>>> start. And lastly I think that it would be a very good idea
> >>>>>> to
> >>>>>> include some more banks in the cooked files this time than we
> >>>>>> did
> >>>>>> before; to find the TDC and ADC values I had to go to the raw
> >>>>>> files
> >>>>>> without any PID info and then cross check between that and the
> >>>>>> cooked
> >>>>>> file to make sure I had the right particle, certainly the SC
> >>>>>> banks
> >>>>>> should be included in the newly cooked files.
> >>>>>> Let me know what you think, if you would like any additional
> >>>>>> information or plots just ask.
> >>>>>> Brian
> >>>>> --
> >>>>> =======================================================
> >>>>> Ken Livingston
> >>>>> Dept. of Physics & Astronomy, Tel: +44 141 330 6428
> >>>>> University of Glasgow, Fax: +44 141 330 5889
> >>>>> Glasgow G12 8QQ.
> >>>>> Scotland. UK.
> >>>>> =======================================================
> >>>>> --
> >>>>> ===============================================================
> >>>>> Franz J. Klein, Associate Professor
> >>>>> CUA, Department of Physics
> >>>>> Washington, DC 20064
> >>>>> office: Hannan Hall 206 phone: 202-319-6190
> >>>>> or: Jefferson Lab,CC F-243 phone: 757-269-6672
> >>>>> ---------------------------------------------------------------
> >>>
> >>>
> >>> --
> >>> =======================================================
> >>> Ken Livingston
> >>>
> >>> Dept. of Physics & Astronomy, Tel: +44 141 330 6428
> >>> University of Glasgow, Fax: +44 141 330 5889
> >>> Glasgow G12 8QQ.
> >>> Scotland. UK.
> >>> =======================================================
> >>
> >
> >
>
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