Tritium transport in the NuMI decay pipe region - modeling and comparison with experimental data

The NuMI (Neutrinos at Main Injector) beam facility at Fermilab is designed to produce an intense beam of muon neutrinos to be sent to the MINOS underground experiment in Soudan, Minnesota. Neutrinos are created by the decay of heavier particles. In the case of NuMI, the decaying particles are created by interaction of high-energy protons in a target, creating mostly positive pions. These particles can also interact with their environment, resulting in production of a variety of short-lived radionuclides and tritium. In the NuMI beam, neutrinos are produced by 120 GeV protons from the Fermilab Main Injector accelerator which are injected into the NuMI beam line using single turn extraction. The beam line has been designed for 400 kW beam power, roughly a factor of 2 above the initial (2005-06) running conditions. Extracted protons are bent downwards at a 57mr angle towards the Soudan Laboratory. The meson production target is a 94 cm segmented graphite rod, cooled by water in stainless tubes on the top and bottom of the target. The target is followed by two magnetic horns which are pulsed to 200 kA in synchronization with the passage of the beam, producing focusing of the secondary hadron beam and its daughter neutrinos. Downstream of the second horn the meson beam is transported for 675 m in an evacuated 2 m diameter beam (''decay'') pipe. Subsequently, the residual mesons and protons are absorbed in a water cooled aluminum/steel absorber immediately downstream of the decay pipe. Some 200 m of rock further downstream ranges out all of the residual muons. During beam operations, after installation of the chiller condensate system in December 2005, the concentration of tritiated water in the MINOS sump flow of 177 gpm was around 12 pCi/ml, for a total of 0.010 pCi/day. A simple model of tritium transport and deposition via humidity has been constructed to aid in understanding how tritium reaches the sump water. The model deals with tritium transported as HTO, water in which one hydrogen atom has been replaced with tritium. Based on concepts supported by the modeling, a dehumidification system was installed during May 2006 that reduced the tritium level in the sump by a factor of two. This note is primarily concerned with tritium that was produced in the NuMI target pile, carried by air flow into the target hall and down the decay pipe passageway (where most of it was deposited). The air is exhausted through the existing air vent shaft EAV2 (Figure 1)

The NuMI Neutrino Beam and Potential for an Off-Axis Experiment

The Neutrinos at the Main Injector (NuMI) facility at Fermilab is under construction and due to begin operations in late 2004. NuMI will deliver an intense $\nu_{\mu}$ beam of variable energy 2-20 GeV directed into the Earth at 58 mrad. Several aspects of the design are reviewed, and potential limitations to the ultimate neutrino flux are described. In addition, potential measurements of neutrino mixing properties are described.Comment: talk given at NuFact '02, Imperial College London, proceedings to appear in J. Phys. G, revised to add a referenc

Beam-Based Alignment of the NuMI Target Station Components at FNAL

The Neutrinos at the Main Injector (NuMI) facility is a conventional horn-focused neutrino beam which produces muon neutrinos from a beam of mesons directed into a long evacuated decay volume. The relative alignment of the primary proton beam, target, and focusing horns affects the neutrino energy spectrum delivered to experiments. This paper describes a check of the alignment of these components using the proton beam.Comment: higher resolution figures available on Fermilab Preprint Server (see SPIRES entry), accepted for publication in Nucl. Instr. and Meth.

Experiment Simulation Configurations Used in DUNE CDR

The LBNF/DUNE CDR describes the proposed physics program and experimental design at the conceptual design phase. Volume 2, entitled The Physics Program for DUNE at LBNF, outlines the scientific objectives and describes the physics studies that the DUNE collaboration will perform to address these objectives. The long-baseline physics sensitivity calculations presented in the DUNE CDR rely upon simulation of the neutrino beam line, simulation of neutrino interactions in the far detector, and a parameterized analysis of detector performance and systematic uncertainty. The purpose of this posting is to provide the results of these simulations to the community to facilitate phenomenological studies of long-baseline oscillation at LBNF/DUNE. Additionally, this posting includes GDML of the DUNE single-phase far detector for use in simulations. DUNE welcomes those interested in performing this work as members of the collaboration, but also recognizes the benefit of making these configurations readily available to the wider community.Comment: 9 pages, 4 figures, configurations in ancillary file

An improved measurement of muon antineutrino disappearance in MINOS

We report an improved measurement of muon anti-neutrino disappearance over a distance of 735km using the MINOS detectors and the Fermilab Main Injector neutrino beam in a muon anti-neutrino enhanced configuration. From a total exposure of 2.95e20 protons on target, of which 42% have not been previously analyzed, we make the most precise measurement of the anti-neutrino "atmospheric" delta-m squared = 2.62 +0.31/-0.28 (stat.) +/- 0.09 (syst.) and constrain the anti-neutrino atmospheric mixing angle >0.75 (90%CL). These values are in agreement with those measured for muon neutrinos, removing the tension reported previously.Comment: 5 pages, 4 figures. In submission to Phys.Rev.Let