Hi,
Is it planned that the recrunch be done with the 6th order Garfield? I can
not see why one ever wants to do that.
the 6th order Garfield has been replaced by my 9th order empirical
polynomials ever since last september and runs earlier than that had been
recrunched with the polynomial t2d calib too.
The empirical method draws directly from successful experiences at CLAS
and TOKYO, was made possible by the fast recrunch using DST. It is based
on the belief that the constraints imposed by the rest 17 wires force the
simulated trajectory pass the wire plane in concern at the "CORRECT"
position and by iterations, the T2D funciton converges in the functional
space to the true t2d funciton.
I believe it has been established that the new calibration has several
advantages:
1. it leads to better and more stable resolutions,
2. elliminates the banding artifacts oberved in proton momentum as occured
with Garfield
3. encoporates the k-factor naturally
4. accomodates errors in wire position, erros and nonlinearlity in TDC
automatically.
There has not been any major crises associated with poor tracking
resolution since we started to use the new calibration. That was when we
started to be able to focus on the systeamtics. I could not imagine a
circumstance why one would revert to the Garfield which, though served as
a great starting point and is used as a fall back whenever there is not
enough statistics to empirically calibrate a wire, caused so much
headaches. Among other things, the banding artifact we once observed will
destroy any attempt to calibrate kinematic offsets using P_{p}.
sorry for the big words and long paragraphs, but I am writing my thesis.
:)
Chi
On Thu, 10 Nov 2005, Chris Crawford wrote:
> A while back it was reported that the recrunch was using the 6th order
> Garfield T2D, but actually it is Chi's. See the following lines (don't know
> how the logic got so twisted!):
>
> ~blast/pro/Blast_Params/blastrc
> # ---- Hits -----
> *.Hit.T0: 6400
> *.Hit.Conv: 0.5
> *.Hit.Vel: 0.00182 # 2.02/1100.
> *.Hit.MaxHits: 1000 # max hits / event
> *.Hit.Cal: on # use t0 calibrations from file
> *.Hit.Dist: on # use nonlinear tdc->distance
> function
> *.Hit.SixthOrder: on # on = 6th order Garfield, off = 3rd
> *.Hit.Hyperbolic: off # on = hyperbolic t2d
> *.Hit.TdcMin: 2000 # 2000=8us (normal range=2us)
> *.Hit.TdcMax: 6600 # full range (close to the wire)
> *.Hit.DistMin: 0 # closest to wire
> *.Hit.DistMax: 9999 # farthest from wire
> *.Hit.Offset: 0.05 # stagger multiple hits
> *.Hit.Color: 2
> *.Hit.Width: 2
>
> *.Hit.9th_cal: true
>
>
> TBLRecon.cc:
> // Linking
> fWire = new TBLWc1WireCal();
>
> if (gOpt->GetValue("Hit.Dist",true)) { // nonlinear t2d
> if(gOpt->GetValue("Hit.9th_cal", true))
> ft2d = new t2d_cal_9th_Order(*fWire);
> else if(gOpt->GetValue("Hit.Hyperbolic",true))
> ft2d = new t2d_hyperbolic(*fWire);
> else if(gOpt->GetValue("Hit.SixthOrder",true))
> ft2d = new t2d_GarField_6th_Order(*fWire);
> else
> ft2d = new t2d_GarField_3rd_Order(*fWire);
> }
> else if(gOpt->GetValue("Hit.Cal", true)) { // improved linear t2d
> ft2d = new t2d_cubic(*fWire);
> }
> else { // simple linear t2d
> ft2d = new t2d_linear();
> }
>
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