Melting LHC detectors: a novel search for stopped long-lived particles

TL;DR

This paper proposes a novel method to detect long-lived particles trapped in LHC detectors by melting detector materials and analyzing the liquid samples, potentially discovering particles up to 3 TeV in mass.

Contribution

It introduces a new approach to recover and analyze trapped long-lived particles from detector materials using melting and mass spectrometry, enhancing detection sensitivity.

Findings

Potential to discover gluinos up to 3 TeV at HL-LHC

Can improve limits for long-lived particles like stops and charged particles

Method enables single-particle sensitivity in macroscopic samples

Abstract

Particles at the TeV scale with lifetimes of a year or longer could have been abundantly produced at the LHC yet escaped detection because of backgrounds, and could still be trapped within detector materials. With gluinos in split-supersymmetry as a working example, we show that these trapped particles can be recovered from detector materials once prepared in liquid form, for example, by melting silicon detectors, extracting liquid argon from the electromagnetic calorimeter, or constructing a large water pool near ATLAS or CMS. These liquid samples can then be processed using iterative centrifugation followed by mass spectrometry, enabling single-particle sensitivity in macroscopic samples. This method can potentially discover gluinos up to 3 TeV in mass at the HL-LHC. It can also improve upon existing limits for other long-lived particles. For example, it can discover the stop up to 2 TeV, and will also be sensitive to integer-charged particles in the TeV range.