Abstract
The recently constructed H4-VLE beam line, a tertiary extension branch of the existing H4 beam line in the CERN North Area, was commissioned in October 2018. The beam line was designed with the purpose of providing very low energy (VLE) hadrons and positrons to the NP-04 experiment, in the momentum range of $1--7\text{ }\mathrm{GeV}/c$. The production of these low-energy particles is achieved with a mixed hadron (pions, kaons, protons), $80\text{ }\text{ }\mathrm{GeV}/c$ secondary beam impinging on a thick target. The H4-VLE beam line has been instrumented with prototype scintillating fiber detectors providing the beam profile, intensity, and time-of-flight measurement of the beam particles, that, together with Cherenkov threshold counters, permit an event-by-event particle identification over the entire momentum spectrum. In this paper, we present detailed results of the beam line performance and the measured beam composition, as well as the comparison of these measurements with simulations performed during the design phase using fluka and geant-4-based Monte-Carlo codes.
Highlights
The production of secondary hadron or lepton beams via the interaction of a primary beam impinging on a target material is the most common technique worldwide for providing experiments or facilities with particle beams of different intensities, compositions and momenta
As discussed in Ref. [7], low energy particles are produced via a secondary beam with a momentum of 80 GeV=c, which is generated in the existing T2 target and transported for ∼600 m through the H4 beam line towards a secondary target
The bending magnets of the H4-very low energy (VLE) beam line are tilted by 56.75° clockwise, and the quadrupoles by 33.25° counterclockwise
Summary
The production of secondary hadron or lepton beams via the interaction of a primary beam impinging on a target material is the most common technique worldwide for providing experiments or facilities with particle beams of different intensities, compositions and momenta. A prominent example of a facility that provides mixed particle beams in the momentum range of 10 to 400 GeV=c is the CERN North Area Secondary Beam facility H. Atherton et al [2] measured the exact composition of secondary particles emitted from the CERN North Area beryllium targets, for different production angles, using the H2 beam line. [2], was subsequently supplemented by the NA-56/SPY experiment [3], that performed measurements of secondary particle production down to 7 GeV=c, starting this time from 450 GeV=c primary protons and impinging on beryllium targets of different lengths. We report on measurements of the particle production rates and relative abundance in the momentum regime of interest of 1–7 GeV=c, along with a comparison to Monte-Carlo simulations
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