| Article | |
| Title | Direct measurement of the formation length of photons |
| Author(s) | Andersen, Kristoffer K (Aarhus U.) ; Andersen, Søren L (Aarhus U.) ; Esberg, Jakob (Aarhus U.) ; Knudsen, Helge (Aarhus U.) ; Mikkelsen, Rune (Aarhus U.) ; Uggerhøj, Ulrik I (Aarhus U.) ; Sona, Pietro (Florence U.) ; Mangiarotti, Alessio (Coimbra U.) ; Ketel, Tjeerd J (Vrije U., Amsterdam) ; Ballestrero, Sergio (Johannesburg U.) |
| Collaboration | CERN NA63 Collaboration |
| Publication | 2012 |
| In: | Phys. Rev. Lett. 108 (2012) 071802 |
| DOI | 10.1103/PhysRevLett.108.071802 |
| Subject category | Particle Physics - Phenomenology |
| Accelerator/Facility, Experiment | CERN SPS ; NA63 |
| Abstract | We report the first observation of a shoulder in the radiation spectrum from GeV electrons in a structured target consisting of two thin and closely spaced foils. The position of the shoulder depends on the target spacing and is directly connected to the finite formation length of a low-energy photon emitted by an ultrarelativistic electron. With the present setup it is possible to control the separation of the foils on a μm scale and hence measure interference effects caused by the macroscopic dimensions of the formation length. Several theoretical groups have predicted this effect using different methods. Our observations have a preference for the modified theory by Blankenbecler but disagree with the results of Baier and Katkov. |
Corresponding record in: Inspire
Záznam vytvorený 2012-11-22, zmenený 2018-03-16
