NA62 objectives

The NA62 experiment aims to measure the very rare kaon decay K+ → π+ν ν at the CERN SPS , to make a decisive test of the Standard Model (SM) by extracting, through a 10% measurement, the Cabibbo–Kobayashi–Maskawa (CKM) parameter |Vtd|.

In order to reach its main goal, NA62 needs to collect about 100 in-flight K+ → π+ν ν events, and to keep the total systematic uncertainty small. Assuming a 10% signal acceptance and a branching ratio of 10-10, at least 1013 K+ decays are required.

To keep the systematic uncertainty small requires a rejection factor, for generic kaon decays, in the order of 1012 and the possibility to measure efficiencies and background suppression factors directly from data.

In addition to the main objective, the NA62 experimental setup will offer the chance to perform many measurements on rare and medium-rare kaon decays. In particular, the good energy resolution for photons will allow the study the radiative kaon decays with unprecedented precision.

Project objectives

During the project (03.2020 - 12.2021), the Horia Hulubei National Institute of Physics and Nuclear Engineering (IFIN-HH) team will contribute in:
- Upgrade of the Hadron Sampling Calorimeter (HASC), doubling its geometrical acceptance;
- Improve the current HASC time resolution;
- Evaluation of NA62 sensitivity to various dark scalar decay channels;
- Maintain and operate HASC during NA62 Phyics Runs, dry-runs, beam and cosmic rays tests;
- Participate at NA62 shifts during NA62Physics Runs, dry-runs, beam and cosmic rays tests.
- Implementation of various biasing schemes in the NA62 Monte Carlo framework


The team is composed by the following R&D personnel from IFIN-HH Particle Physics Department:
- Dr. Alexandru-Mario BRAGADIREANU - research scientist;
- Ovidiu-Emanuel HUTANU - electronics engineer;
- Stefan-Alexandru GHINESCU - physicist;
- Petre BOBOC - physicst;
- Neagu IONEL - technician;
- Alina Motorga - accountant;


I. Assembly of the second Hadronic Sampling Calorimeter (HASC)

Activity I.1: Production, assembly and testing of HASC FEE and mechanical supports for 18 HASC modules;
Activity I.2: Production, assembly and testing of HASC HV&LV distribution and temperature controlloer.

II. Studies on HASC

Activity II.1: We elaborated a method for the calibration of the HASC signal. The figure below shows the spectrum of amplitudes of the signals coming from cosmics rays (in blue dots) and the fit (in red) using our model.

HASC calibration

Fig.1 - HASC signal calibaration with cosmics

Activity II.2: At the request of the collaboration, we performed an MC simulation in order to determine the optimal placement of the new HASC station. The figure below shows this position to be symetrical to the old station with respect to the beampipe.

New HASC position

Fig.2 - Distribution of electrons (blue) and positrons (red) at the front plane of HASC

III. Implementation of variance reduction techniques

Activity III.1: We have modified the Geant4 K+ inelastic process to always emit a KS of momentum above 20 GeV/c, while accounting for the probability (weight) of this to occur. The figure below shows the enhancement of useful statistics (green) induced by this biasing technique

KS biasing

Fig.3 - Decay Z position of KS in biased (left) and analog (right) MC productions

Publications and talks


List of publications