# Search for Ultra-High-Energy Neutrinos with the Telescope Array Surface Detector

## TL;DR

This paper reports an upper limit on ultra-high-energy neutrino flux using nine years of Telescope Array surface detector data, employing a multivariate Boosted Decision Trees method to distinguish neutrino-induced showers.

## Contribution

It introduces a novel application of BDTs with 16 observables to identify ultra-high-energy neutrinos in surface detector data.

## Key findings

- Established an upper flux limit for neutrinos above 10^18 eV.
- Demonstrated the effectiveness of multivariate analysis in neutrino detection.
- Provided constraints for models of ultra-high-energy neutrino sources.

## Abstract

We present an upper limit on the flux of ultra-high-energy down-going neutrinos for $E > 10^{18}\ \mbox{eV}$ derived with the nine years of data collected by the Telescope Array surface detector (05-11-2008 -- 05-10-2017). The method is based on the multivariate analysis technique, so-called Boosted Decision Trees (BDT). Proton-neutrino classifier is built upon 16 observables related to both the properties of the shower front and the lateral distribution function.