Study of a hadron monitor for long baseline neutrino facility

Abstract

Hadron monitor (HM) plays an important role in inferring or estimating the properties of a neutrino beam by measuring the secondary hadrons in the beam. The HM is also used for the alignment of the primary beam on the production target and for the beam status monitoring during operation. Since HM is permanently placed in the beam line, it has to be robust enough to endure high-level radiation when beam is on. Considering very large dynamic ranges for the beam size and current in different machine modes at the Long Baseline Neutrino Facility (LBNF), an HM in multi-strip secondary electron emission (SEM) type was proposed to meet all the requirements. This paper presents a simulation study of several key issues related to the multi-strip HM, such as energy deposition, signal level estimation and vacuum in a long pipe. A test stand has been setup for measuring the sag in the strips at different temperature that imitates the energy deposition of beam in the strips. The measurements show that with appropriate tension applied, the sag can be easily controlled within a few micrometers.