# NA62

CP3 - Research directions and experiments
NA62 is an experiment at SPS accelerator at CERN that has as objective the measurement of the rare decay $K^+ \rightarrow \pi^+ \nu \bar{\nu}$. It's now in approbation phase.

Our group is contributing in the design and construction of the pixel detector of this experiment.

## Projects

Click the title to show project description.
• Gigatracker is in the core of one of the spectrometers used in NA62. It's composed of three planes of silicon pixels detectors assembled in a traditional way: readout electronics bump bonded on silicon sensors. Each plane is composed by 18000 pixels 300 um x 300 um arranged in 45 columns and readout by 10 chips. The particularity of this sensor is that its timing resolution should be better than 200 ps in order to cope with high expected rate (800 MHz). Another particularity is its operation in vacuum.

CP3 is involved in several aspects in the production and operation of this detector.

1) Production of 25 GTK stations that will be used during the NA62 <latex>$K^+\to\pi^+\nu\bar{\nu}$</latex> run

2) Operation of GTK during data taking: time and spatial calibration, efficiency studies, effects of radiation, ....

3) Track candidates reconstruction, simulation.

4) Signal development of the signal in the sensor. We use both commercial programs (i.e. TCAD by Synopsys) as well as software developed by us to study the expected signal in this sensor.

• The NA62 experiment in the North Area of the CERN SPS is now fully operational and taking data. The plan is to collect the highest statistics ever reached for <latex>$K^+$</latex> decays, of the order of <latex>$10^{13}$</latex> events in the fiducial decay region of the detector until the end of 2018. This high-intensity and high-precision setup makes it possible to probe a number of ultra-rare or forbidden decay channels. Of particular interest to the CP3 group are the LFV/LNV <latex>$K^+ \rightarrow \pi^{+}\mu^{\pm}e^{\mp}$</latex> and <latex>$K^+ \rightarrow \pi^{-}l^+l'^+ (l,l' = e,\mu})$</latex> modes.

Many BSM theories predict some degree of LFV, including Supersymmetry or the introduction of massive neutrinos. Furthermore, there are indirect hints for New Physics in the flavor sector, e.g. in the semileptonic decays of B-mesons. Explanations for the observed discrepancies predict effects of LFV in kaon decays. These particular LFV/LNV <latex>$K \rightarrow \pi ll$</latex> processes which at present are not covered by another experiment provide an attractive opportunity to test the SM. Any observable rate for one of these modes would constitute unambiguous evidence for New Physics. Considering the statistics that will be available at NA62 the current limits on their branching-ratios could be improved by at least one order of magnitude.

• NA62 will look for rare kaon decays at SPS accelerator at CERN. A total of about $10^{12}$ kaon decays will be produced in two/three years of data taking. Even though the topology of the events is relatively simple, and the amount of information per event small, the volume of data to be stored per year will be of the order of ~1000 TB. Also, an amount of 500 TB/year is expected from simulation.

Profiting from the synergy inside CP3 in sharing computer resources our group is participating in the definition of the NA62 computing scheme. CP3 will be also one of the grid virtual organization of the experiment.

## Recent Publications

Click the title to show details.
• Buonocore, Luca and Frugiuele, Claudia and Maltoni, Fabio and Mattelaer, Olivier and Tramontano, Francesco, December 3, 2018
Refereed paper. [Abstract] [PDF] [Journal] [Dial]

• Drewes, Marco and Hajer, Jan and Klaric, Juraj and Lanfranchi, Gaia, June 11, 2018
Refereed paper. Contribution to proceedings. [Abstract] [PDF]

• Drewes, Marco and Hajer, Jan and Klaric, Juraj and Lanfranchi, Gaia, January 15, 2018
Refereed paper. [Abstract] [PDF] [Journal] [Dial]

• S. Podolsky, E. Cortina, N. Lurkin, April 5, 2012
Contribution to proceedings. [Full text]

• CERN NA62 collaboration: C. Lazzeroni et al., January 27, 2011
Refereed paper. [Abstract] [PDF] [Journal] [Dial]

• Eduardo Cortina Gil, February 17, 2009
Contribution to proceedings. [Full text]