NA63 experiment
The NA63 experiment aims to study the
This experiment is part of the SPS research programme and began taking data in 2010 with Mr Ulrik Ingerslev Uggerhoj as spokesperson.[1]
Critical fields in crystalline targets
One of the main objectives of NA63 is to study the trident “Klein-like” production. This phenomenon happens in very strong electromagnetic fields, when an electron in motion penetrates the field and emits an
In such fields, an electron may gain an energy corresponding to the production of a new electron-positron pair, if it is transported over a distance given by the quantum mechanical uncertainty of its location : Δd= ƛ = ħ/mc. Thus, significant production of new particles is expected – and observed[2] – once the field in the electron rest frame becomes critical.
Such fields are generally only seen in astrophysical phenomena, such as highly magnetized neutron stars, black holes (where it is the gravitational field that is strong instead of the electromagnetic field as in NA63) where the Hawking radiation is a close analogue and, perhaps, in the cosmic accelerators that give rise to cosmic rays of the highest known energies. Using a special approach employing crystalline targets and energetic beams from the SPS (~ 100GeV), NA63 has managed to test processes at such fields in the laboratory.
Emission times
Another line of enquiry for NA63 is the effect of strong electromagnetic fields on the duration of the process of photon emission. Specifically, fields of a critical magnitude have an intriguing effect on how long it takes for an electron to emit a photon.
An electron entering an electric field is accelerated, and therefore must lose part of its energy in the form of a photon via the Bremsstrahlung effect - the process by which a charged particle emits electromagnetic radiation when being decelerated upon passing an atom, for instance in a solid material. By exploiting the relativistic phenomena of
In a critical electromagnetic field, on the contrary, electrons are deflected so violently that they don't have enough time to radiate photons. So adjusting the electromagnetic field past a critical level can modify the emerging radiation spectrum of a beam of electrons: increase the field and the relative radiation yield from the beam diminishes. NA63 is investigating such effects, and one of the main results shown so far is the measurement of quantum corrections to synchrotron radiation[5] that is normally only observed in its classical form in a synchrotron (storage) ring.
Radiation Reaction
Radiation reaction is a long-standing problem in
Effects
The effects of strong fields and emission times are relevant in many other branches of physics, ranging from the so-called “bubble-regime” in
The Unruh effect might have been observed for the first time in the high energy channeling radiation explored by NA63.[7][8]
NA63 active collaboration members
- Christian Flohr Nielsen (spokesperson): https://orcid.org/0000-0002-8763-780X
- Ulrik Uggerhøj : http://orcid.org/0000-0002-8229-1512
- Tobias Wistisen: https://orcid.org/0000-0001-8103-9860
- Robert Holtzapple: http://orcid.org/0000-0003-2726-1131
- Antonino Di Piazza: https://orcid.org/0000-0003-1018-0458
- Simon H. Connell: http://orcid.org/0000-0001-6000-7245
- Jens Bo Justesen: https://orcid.org/0000-0003-2525-6793
- Allan H. Sørensen.
- Mads Middelhede Lund https://orcid.org/0000-0001-9859-9506
- Marc Breiner Sørensen
- Sofie Jastrup Lanng
External links
- CERN-NA-063 experiment record on INSPIRE-HEP
- Cosmic rays : particles from outer space : https://home.cern/about/physics/cosmic-rays-particles-outer-space
- Heavy ions collisions : https://home.cern/about/physics/heavy-ions-and-quark-gluon-plasma
References
- ^ "NA63". CERN. 2015-01-05. Retrieved 2018-07-07.
- ^ a b c
Esberg, J.; Kirsebom, K.; Knudsen, H.; Thomsen, H. D.; Uggerhøj, E.; Uggerhøj, U. I.; Sona, P.; Mangiarotti, A.; Ketel, T. J.; Dizdar, A.; Dalton, M. M.; Ballestrero, S.; Connell, S. H. (2010). "Experimental investigation of strong field trident production". Physical Review D. 82 (7): 072002. ISSN 1550-7998.
- ^
Uggerhøj, Ulrik I. (2005). "The interaction of relativistic particles with strong crystalline fields". Reviews of Modern Physics. 77 (4): 1131–1171. ISSN 0034-6861.
- ^
Andersen, Kristoffer K.; Andersen, Søren L.; Esberg, Jakob; Knudsen, Helge; Mikkelsen, Rune; Uggerhøj, Ulrik I.; Sona, Pietro; Mangiarotti, Alessio; Ketel, Tjeerd J.; Ballestrero, Sergio (2012). "Direct Measurement of the Formation Length of Photons". Physical Review Letters. 108 (7): 071802. PMID 22401193.
- ^
Andersen, K. K.; Esberg, J.; Knudsen, H.; Thomsen, H. D.; Uggerhøj, U. I.; Sona, P.; Mangiarotti, A.; Ketel, T. J.; Dizdar, A.; Ballestrero, S. (2012). "Experimental investigations of synchrotron radiation at the onset of the quantum regime". Physical Review D. 86 (7): 072001. S2CID 118488702.
- ^
Di Piazza, A.; Wistisen, Tobias N.; Uggerhøj, Ulrik I. (2017). "Investigation of classical radiation reaction with aligned crystals". Physics Letters B. 765: 1–5. S2CID 117037721.
- ^ a b
Wistisen, Tobias N.; Di Piazza, Antonino; Knudsen, Helge V.; Uggerhøj, Ulrik I. (2018). "Experimental evidence of quantum radiation reaction in aligned crystals". Nature Communications. 9 (1): 795. PMID 29476095.
- ^
Lynch, M. H.; Cohen, E.; Hadad, Y.; Kaminer, I. (2021). "Experimental Observation of Acceleration-Induced Thermality". S2CID 214623535.