Hi Chris,
please give the large map a different name that will be specified in
.blastrc. Also, Doug's new map should be bgrid3.blast. Different versions
in CVS with the same filename are only justified if there are bugfixes to
an existing map.
Regards,
Michael
On Tue, 4 Oct 2005, Chris Crawford wrote:
> Hi Doug,
> I copied the file to
> /home/daq/blast/pro2004/Blast_Params/bgrid2.blast, and checked it in
> (version 1.9). Note that cvs_v3/Blast_Params is not used, and also the
> '2' in bgrid2.blast, and #2 in the first line refer to the file format,
> not version of the map. I also fixed the first line.
> I started 'setenv ANALDIR test-2005-10-04; lrn +SQL 12144' from the
> blast acct to test the new field.
> We can either check the larger map as a new version of bgrid2.blast,
> or with a new name like 'bgrid2.large', making it easier to switch back
> and forth. Which do you think would be better?
> --Chris
>
>
> Douglas Kenneth Hasell wrote:
> >
> > Hi,
> >
> > I have put a file "bgrid3.blast" into the Blast_Params sub-
> > directory of the blast account. I have not done anything else and hope
> > someone who knows what they are doing can take the appropriate action.
> >
> > This file has the same ranges (ie size) as the previous grid files
> > so no changes are needed to the code other than whatever is necessary
> > to have the field calculating code point at this file rather than
> > bgrid2.blast.
> >
> > The new file "bgrid3.blast" is based on the field mapping data from
> > Abby Goodhue "TOT.dat". I used her results but edited to remove any
> > point which differed by more than 200 G from the Biot-Savard
> > calculation (this had the effect of removing about 150 bad points). I
> > then fit the mapped data allowing the coils to move and obtained a
> > good fit with R = -8.1 mm, Z = 8.09 mm, and some small angle changes.
> >
> > I then filled the desired grid with the closest mapped result if
> > one existed and with the offset coil calculated result if no mapped
> > data was close. If the calculated point is greater than 4000 G (which
> > can happen close to the coils) I fix its magnitude to 4000 G to reduce
> > the non-linearities near the coil. Then, since the mapped values are
> > not exactly on the grid points I loop over the grid points and
> > determined the field at the grid point by fitting a second order
> > polynomial in x, y, and z to the 27 points surrounding the desired grid
> > point. I do this so long as at least one point of the 27 was a
> > measured value. If all 27 are calculated there is no need to do the fit.
> >
> > I am now calculating a new grid following the same procedure as
> > above but changing the ranges so that the grid extends to the TOF's in
> > x, y, and z and also extends back to Z = -1.2 m to include the BAT's
> >
> > The old range was
> >
> > -200 <= x <= 200
> > -70 <= y <= 70
> > -10 <= z <= 290
> >
> > The new range I am calculating now is:
> >
> > -250 <= x <= 250, 101 grid steps
> > -90 <= y <= 90, 37 grid steps
> > -120 <= z <= 380, 101 grid steps
> >
> > For comparison the y component of the field at
> >
> > x = 200, y = 0, z = 0 is -454 G
> > x = 250, y = 0, z = 0 is -95 G (near face of back angle TOF)
> >
> > x = 130, y = 0, z = 290 is -269 G
> > x = 130, y = 0, z = 380 is 10 G (near face of forward angle TOF)
> >
> > This new grid will be approximately 2.6 times larger. If anyone
> > thinks this too large please let me know.
> >
> >
> >
> > Cheers,
> >
> > Douglas
> >
> > 26-415 M.I.T.
> > Tel: +1 (617) 258-7199
> > 77 Massachusetts Avenue Fax: +1 (617)
> > 258-5440
> > Cambridge, MA 02139, USA E-mail:
> > hasell@mit.edu
>
>
--+-------------------------------------+--------------------------+ | 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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