I agree with Chi, his calibration is a great improvement. I just
wanted to make sure we are all on the same page!
--Chris
ps. Chi, looks like you now have a few more paragraphs for your thesis!
On Nov 10, 2005, at 11:08:26, Chi Zhang wrote:
>
> 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 the 6th order Garfield has been replaced by my 9th order empirical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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