The Pion Formfactor Experiment

HEEP Check Results---Summary

The following results are analyzed near Fri May 23 16:11:11 EDT 2003.

Abstract

In this page, we do some heepcheck summarization. All we do here is suppose that the HMS is perfect, the angle of SOS is perfect, so only Psos and Ebeam should have additional offset calibration.

In section (2) we do some heepcheck practise for Psos=1.2 GeV and Psos=1.74 GeV seperately. In section (3) we list the value of offsets for different Psos. In section(4) we replay these runs with these new offsets put into kinematic file and see the improvements. In section (5) we compare the improvements in different ssdelta region (ssdelta=0.0 and ssdelta=13) at Psos=1.74 GeV.

In out performance, we set the old saturation correction for Psos on, so what we have here is an offset added to the original correction. If the relative saturation correction for Psos is correct, we should see the same improvement in Psos=1.74 GeV. Unfortunately this is not true.

We have already had Psos=1.2 GeV/c point and Psos=1.74 GeV/c points. If we want to make our own curve of saturation correction for Psos, we need more heepcheck runs at 0.9 GeV/c, 1.4 GeV/c , 1.6 GeV/c, or even 1.76 GeV/c points.

(1) Introduction

Since we have done heepcheck fitting on Psos=1.2 GeV/c and Psos=1.74 GeV/c, it's necessary to get a summarization here.

(2) Results for heepcheck for different runs

In Psos=1.2 GeV/c, we get (in run 45162)
dW: -0.81e-2 GeV/c2
Emiss: -0.78e-2 GeV
Pm par: -0.278e-2 GeV/c
Pm per: -0.606e-2 GeV/c
Pm oop: 0.511e-2/c GeV/c
In this run Ebeam=2238.0 MeV, and sostheta=50.405

Now I accept Henk's results as well as the pricipal of how to be a good physicist here.
Then I get
Our own de0, dthe, dpe, dthp, dpp:
-1.0 0.0 4.0 0.0 0.0
would lead to the following:
dW dE_m dp_m(par) dp_m(perp)
-10.16 -7.04 -2.52 -5.95

In Psos=1.74 GeV/c, we get (in run 45906)
dW: -0.81e-2 GeV/c2
Emiss: -0.6245e-2 GeV
Pm par: -0.1183e-2 GeV/c
Pm per: -0.5844e-2 GeV/c
Pm oop: 0.7445e-2 GeV/c

Our own de0, dthe, dpe, dthp, dpp:
0.0 0.2 3.0 0.0 0.0
would lead to the following:
dW dE_m dp_m(par) dp_m(perp)
-9.87 -5.22 -1.21 -5.09

(3) Summary

(a) In the same kinematics, different runs give similar deviations , so in each case we only took one as an example. (In 1.2 GeV/c, run 45162 and in 1.74GeV/c, run 45906)

(b) The offset for E0, theta(e), Pe, theta(P), Pp are
1.0 0.0 -4.0 0.0 0.0 for 1.2 GeV/c
and
0.0 -0.2 -3.0 0.0 0.0 for 1.74 GeV/c

(4) Conclusion

We apply the offset get from Psos=1.2 GeV case as a universal offset, in standard.kinematics file. And replay run 45162, 45165, 45906 and 45907 again. Then I get the following results:

For run 45162:
dW: +0.2e-2 GeV/c2
Emiss: -0.1e-2 GeV
Pm par: -0.44e-3 GeV/c
Pm per: -0.70e-4 GeV/c
Pm oop: 0.50e-2 GeV/c

Fig.1 and Fig.2 are the Figures done after our new heepcheck correction for Psos=1.2 GeV.

Fig.1 W, Emissing distribution at Psos=1.2 GeV from run 45162. Done after our new heepcheck correction.

Fig.2 Pm,Pm_par, Pm_per, Pm_oop distribution at Psos=1.2 GeV from run 45162. Done after our new heepcheck correction.

For run 45165:
dW: +0.2e-2 GeV/c2
Emiss: -0.106e-2 GeV
Pm par: -0.508e-3 GeV/c
Pm per: -0.44e-4 GeV/c
Pm oop: 0.475e-2 GeV/c

For run 45906:
dW: +0.55e-2 GeV/c2
Emiss: 0.36e-2 GeV
Pm par: 0.34e-2 GeV/c
Pm per: -0.44e-4 GeV/c
Pm oop: 0.475e-2 GeV/c

Fig.3 and Fig.4 are the Figures done after our new heepcheck correction for Psos=1.74 GeV.

Fig.3 W, Emissing distribution at Psos=1.74 GeV from run 45906. Done after our new heepcheck correction.

Fig.4 Pm,Pm_par, Pm_per, Pm_oop distribution at Psos=1.74 GeV from run 45906. Done after our new heepcheck correction.

For run 45907:
dW: +0.56e-2 GeV/c2
Emiss: 0.38e-2 GeV
Pm par: 0.31e-2 GeV/c
Pm per: -0.5e-4 GeV/c
Pm oop: 0.5e-2 GeV/c

So it seems that the offset is OK for low momentum, but when the momentum is as large as 1.74 GeV, saturation effect is important. And it seems that the original saturation correction in the code still need to be modified.

But unfortunately we only have two points. How can we fit a formula? Now I understand why Henk said "too bad we do not have heepcheck at Psos=1.4 and 1.6 GeV/c."

The value Pm oop is supposed to be zero. But here we seem to have a 0.5e-2 GeV/c. Is this a tolerable value? What can we do to it if the answer is no? It is not included in heep programme.

Welcome Eric to give suggestions and comments.

(5) Appendix--heepcheck improvements at other ssdelta value?

In run 45912, we have another run of Psos=1.74 GeV. It correcpond to ssdelta=12, which is in an acceptable delta scope according to delta scan.
For run 45912,now we list the dW Emiss, Pmiss as follows :
(a) is before applying new heepcheck offset
(b) is after applying new heepcheck offset

dW:-----(a) -0.97e-2 GeV/c2--(b) 0.4e-2
Emiss:--(a) -0.74e-2 GeV-----(b) 0.329e-2
Pm par:-(a) -0.18e-2 GeV/c----(b) 0.242e-2
Pm per:-(a) -0.708e-2 GeV/c---(b) 0.201e-2
Pm oop:-(a) 0.807e-2 GeV/c----(b) 0.80e0-2

As comparison, we list the same thing for run 45906 as follows:

dW:-----(a)-0.81e-2 GeV/c2----(b) 0.55e-2 GeV/c2
Emiss:--(a)-0.6245e-2 GeV-----(b) 0.36e-2 GeV
Pm par:-(a)-0.1183e-2 GeV/c---(b) 0.34e-2 GeV/c
Pm per:-(a)-0.5844e-2 GeV/c---(b) 0.44e-4 GeV/c
Pm oop:-(a)0.7445e-2 GeV/c----(b) 0.475e-2 GeV/c

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