Speaker
Description
The contribution of simulations in muographic measurements is crucial for the correct interpretation of data and for the estimation of the average density of the target along the detector lines of sight. One of the dominant sources of uncertainty in the density reconstruction arises from the model used to parameterize the differential flux of atmospheric muons at ground level in the simulation framework. This systematic effect can reach values as large as 10%. Such models are often based on experimental datasets collected by different detectors, characterized by distinct systematic uncertainties, covering different energy ranges and acquired at geographical locations that do not necessarily match those where the muographic measurements are performed.
In this context, the ACROMASS experiment, developed by INFN Florence and University of Florence, represents an upgrade of the ADAMO experiment. ADAMO was a magnetic spectrometer that collected data in 2004 at the latitude of Florence, but it did not allow particle identification (PID). Its dataset has been used as a reference for some of the muon generators employed in muography, such as EcoMug implemented in GEANT4. ACROMASS is designed as a portable, low-power magnetic spectrometer equipped with a set of sub-detectors enabling particle identification in the energy range 100 MeV–250 GeV. The detector consists of three subsystems: a Time-of-Flight (TOF) system, a magnetic spectrometer, and an electromagnetic calorimeter. Its lightweight and transportable design allows measurements to be performed also at high altitude.
The experiment will contribute to a more accurate calibration of the models used in muographic simulations, potentially reducing the systematic uncertainty on differential muon fluxes below 5%, even at low energies (<1 GeV), where electron and positron contamination is significant. Moreover, ACROMASS will enable online measurements of the muon flux simultaneously with ongoing muographic data taking and at the same geographical location, thereby reducing uncertainties related to atmospheric and solar variations, which can exceed 20%.
In this work, the ACROMASS detector will be presented together with some preliminary results obtained from two test beams performed at CERN in Geneva.