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chisq/dof plot attached - I'm using TGraph to fit, which assumes errors of 1 mV per data point. I use the time range (-200, 60). On Thu, 3 Apr 2014, Gabriel CHARLES wrote: > Could you both provide an average value of chi square that the different > parametrization can be compared easily, please ? > > Also, from the simulation it appears that the rising edge could be present. > In attachment you will find a picture with two plots. The top one corresponds > to the signal after the crystal and the APD, that is the input of the > preamplifier. > It is obtained by the convolution of the signal of the crystal and the APD. > The crystal response is composed of the sum of two decreasing exponential > governed by different time constants. The APD transfert function is given by > the bottom plot (sorry for the wrong Y axis units). > > There is no reason for the preamplifier to reduce the tail. > > I think that if there is no huge difference between the chi square it would > be better to keep the two gaussian function. > > --- > Gabriel CHARLES > Institut de Physique Nucléaire d'Orsay > > On Thu, 3 Apr 2014 13:15:00 -0700 (PDT), Sho Uemura wrote: >> I tried two more parametrizations. These are parametrizations >> commonly used for the APV25 preamp that we use in the SVT. >> >> CR-RC: t*exp(-t/tp) >> 3-pole, or CR-RC-RC: t^2*exp(-t/tp) >> >> 3-pole seems to fit well, I think better than the asymmetric >> Gaussian. CR-RC seems no better than the Gaussian. Other >> parametrizations I tried (variations on CR-RC or 3-pole using more >> than one time constant) were degenerate with CR-RC or 3-pole, so I >> didn't include those plots. >> >> Plots attached are for 3-pole function. All plots for 3-pole and >> CR-RC, and the pyroot scripts I used, are online: >> >> http://www.slac.stanford.edu/~meeg/ecalpulsefit/ >> >> I also see what you see, where there are 2 clusters in the >> distribution of shape parameters. I chose the center of the larger >> cluster (with the faster time constant) and refit all the events with >> this time constant fixed; those plots are named "fit2" and as expected >> they fit the faster pulses well and the slower pulses poorly. >> >> More data will help. >> >> I plotted the three parametrizations we have, see plot4.pdf attached. >> If we agree that the Gaussian has an unphysical rising edge, I think >> we should use 3-pole. >> >> On Tue, 1 Apr 2014, Andrea Celentano wrote: >> >>> Dear all, >>> here are some results about HPS Ecal signals parametrization. >>> I took data with the crystal placed vertically, APD gain 150, room >>> temperature. I put a threshold ~ 20 mV to keep only big enough signals, >>> out of the noise. >>> I acquired data with a 2.5Gs/s oscilloscope, 1 GHz bandwidth, 50 Ohm input >>> impedance. >>> >>> I used the same* configuration employed at JLab for cabling: 8m 3M cable >>> ---> passive splitter ---> 3m lemo cable. >>> >>> *actually I employed an 8 meters 3M cable instead of 7m because the latter >>> is not available here in Genova. >>> >>> Attached you find a postcript file with the results. (outGood.ps shows the >>> fit results covering some parts of the signal, outGood1.ps no) >>> >>> - Neglect first blank page >>> - Pages from 2 to 32 are the 31 signals I got, with superimposed the fit >>> performed with the two-gaussians parametrization. Each chi2 fit is >>> performed independently. >>> Signals are in mV and ns. >>> Note that near ~ 100 ns there is probably a reflection due to some >>> impedance mismatch in the cables chain. >>> However, I am not using those points to fit. I am fitting the data in >>> between -200 ns and +80 ns. The function is then plotted in the full time >>> range. >>> >>> - Last page is a summary of the fits performed. Two 1d-histograms are the >>> distributions of the two time constants used in the parametrization. Then >>> I am plotting also their correlation, as well as the correlation of the >>> rise-time (par[1]) with the signal amplitude (from the fit). >>> >>> I noted that the fit parameters Trise, Tfall are not distributed as two >>> gaussians. In particular, for Trise there is an accumulation of events at >>> ~ 5 ns and ~ 7 ns, correlated with corresponding Tfall at ~ 15 and ~20 ns. >>> Actually, I see that, other than the amplitude, signals do not have always >>> the same shape: look, for example, at signals n.5 and n.6 (ps pages n.5 >>> and n.6). >>> >>> Attached you find also the C implementation of the signal parametrization, >>> in form of a "double fun(double *x,double *par)" used by ROOT when >>> fitting trough TF1. >>> Finally, I am attaching also the raw data for the 31 signals I got, so if >>> you're interested you can play with different signal parametrizations. >>> >>> I am planning to take more data these days. >>> >>> >>> Bests, >>> >>> Andrea >>> > > ######################################################################## > Use REPLY-ALL to reply to list > > To unsubscribe from the HPS-SOFTWARE list, click the following link: > https://listserv.slac.stanford.edu/cgi-bin/wa?SUBED1=HPS-SOFTWARE&A=1 > ######################################################################## Use REPLY-ALL to reply to list To unsubscribe from the HPS-SOFTWARE list, click the following link: https://listserv.slac.stanford.edu/cgi-bin/wa?SUBED1=HPS-SOFTWARE&A=1