# ICARUS (experiment)

ICARUS (Imaging Cosmic And Rare Underground Signals) is a physics experiment aimed at studying neutrinos. It was located at the Laboratori Nazionali del Gran Sasso (LNGS). No longer operating, it is being refurbished at CERN for re-use in the same neutrino beam from Fermilab as the MiniBooNE experiment.[1]

The ICARUS program was initiated by Carlo Rubbia in 1977, who proposed a new type of neutrino detector.[2] These are called Liquid Argon Time Projection Chambers (LAr-TPC), which should combine the advantages of bubble chambers and electronic detectors. In the course of the ICARUS program, such detectors of considerable capacity were proposed. After first runs at Pavia in 2001, the ICARUS T600 detector at Gran Sasso, filled with 760 tons of liquid argon, started operation in 2010. In order to study neutrino oscillations and various fundamental topics of modern physics, neutrinos of astronomic or solar sources, and CERN Neutrinos to Gran Sasso (CNGS) produced 730 km away by the Super Proton Synchrotron from CERN, have been detected through the reaction:[3]

${}^{40}Ar + \nu \rightarrow {}^{40}K + e^{-} \,.$

The CNGS neutrinos are also studied by the OPERA experiment, therefore those experiments are also called CNGS1 (OPERA) and CNGS2 (ICARUS).[4]

The CNGS measurements also became important when the OPERA group announced in September and November 2011, that they have measured superluminal neutrinos (see faster-than-light neutrino anomaly). Shortly afterwards, the ICARUS collaboration published a paper in which they argued, that the energy distribution of the neutrinos is not compatible with superluminal particles. This conclusion was based on a theory of Cohen and Sheldon Lee Glashow.[5] In March 2012, they published a direct neutrino velocity measurement based on seven neutrinos events. The result was in agreement with the speed of light and thus special relativity, and contradicts the OPERA result.[4] In August 2012, another neutrino velocity measurement based on 25 neutrino events was published with increased accuracy and statistics, again in agreement with the speed of light,[6] see measurements of neutrino speed.

## References

1. ^ Jepsen, Kathryn (22 April 2015). "Italian neutrino experiment to move to the US". Symmetry magazine. Retrieved 2015-05-08.
2. ^ Rubbia, C. (1977). "The liquid-Argon time projection chamber: a new concept for neutrino detector" (PDF). CERN. CERN-EP/77-08.
3. ^ ICARUS-Collaboration (2011). "Underground operation of the ICARUS T600 LAr-TPC: first results". Journal of Instrumentation 6 (07): 7011. arXiv:1106.0975. Bibcode:2011JInst...6.7011R. doi:10.1088/1748-0221/6/07/P07011.
4. ^ a b ICARUS Collaboration (2012). "Measurement of the neutrino velocity with the ICARUS detector at the CNGS beam". Physics Letters B 713 (1): 17–22. arXiv:1203.3433. Bibcode:2012PhLB..713...17I. doi:10.1016/j.physletb.2012.05.033.
5. ^ ICARUS Collaboration (2012). "A search for the analogue to Cherenkov radiation by high energy neutrinos at superluminal speeds in ICARUS". Physics Letters B 711 (3-4): 270–275. arXiv:1110.3763. Bibcode:2012PhLB..711..270I. doi:10.1016/j.physletb.2012.04.014.
6. ^ ICARUS collaboration (2012). "Precision measurement of the neutrino velocity with the ICARUS detector in the CNGS beam". Journal of High Energy Physics (11): 49. arXiv:1208.2629. Bibcode:2012JHEP...11..049A. doi:10.1007/JHEP11(2012)049.