Meeting No 25

We are searching for the missing effect that causes 10% lack of events in the elastic peak!

Changing external radiative corrections

Increasing the external radiative corrections bings the elastic events to the correct position but causes the excess of the inelastic events in the first part of the tail. : See the effect, when the external corrections are increased for factor "2" and "ln2":

Changing Landau distribution

Alternatively one could increase the width of the Landau distribution. When doing that one learns, that while elastic events are now in the agreement there is a lack of the events in the first part of the tail. Here is what happens if we increase the width of Landau for factor 1.5

Combining both effects together

Since External radiative corrections and Landau losses cause mirror effects in the first part of the tail, it seems that both effects need to be corrected simultaneously. This way we bring elastic events to an agreement without distorting the shape of the tail.

Since both effects depend on the surface density of the material, it must be some material that is missing. It could not be a mistake in the LH2, because, we did not make a 20% mistake in determining the density of the hydrogen. It can only be Cryogens on the the exit windows, that are not visible with our methods. If we increase the width of the snow to about 0.5mm (200x more than on the entrance window), we get the spectra we want.

Results for setting 495_08

Before and after correction of the snow on the side. On the side, there is 200x more snow than on the entrance and exit windows:

Present results:

New results for 495MeV with smaller statistics but with elastic points now included.

Last modified 07/04/2017