| Popis: |
In the NA63 experiment of April 2018 reliable data was taken for 40 and 80 GeV electrons and positrons aligned to the $\langle100\rangle$ axis of a diamond crystal of thickness 1.5 mm, as well as for 40 and 80 GeV electrons on a 1.0 mm thick diamond aligned to the $\langle100\rangle$ axis. A paper has been submitted to Phys.\ Rev.\ D, and has received favourable referee comments. For the 2017 data, a paper has been published in Phys.\ Rev.\ Research in 2019, and our experimental findings have inspired another paper published in Phys.\ Rev.\ Lett.\ \\ For the year 2021 we request 2 weeks of beamtime in the SPS H4 to do a measurement of trident production, $e^-\rightarrow e^-e^+e^-$, in strong crystalline fields. This process is closely related to the production of muon pairs, $e^-\rightarrow e^-\mu^+\mu^-$, and single crystals may prove to be an attractive source to obtain muons of high intensity and small emittance, as required for a muon collider. The trident results obtained in 2009, and published in 2010, are strongly at odds with theory (factor 3-4 discrepancy). Since then we have acquired and have been using MIMOSA-26 position-sensitive detectors with a resolution about a factor 40 higher than the drift chambers used in 2009, and now with true multi-hit capability, a significant advantage when looking for trident events. Thus we have substantial improvements in our equipment that enable a much more precise measurement. |
