Low energy tertiary beam line design for the CERN neutrino platform project

In the framework of CERN neutrino platform project at the CERN SPS North Area, two new beam lines have been designed as extensions of the existing secondary beam lines, able to provide low energy particles in the momentum range of 0.4 to $12\mathrm{GeV}/c$. The layout of these very low energy beam lines, their design parameters as well as outlook on their expected performance, are summarized in this paper.

Figure 1

3D drawing of the EHN1 hall. On the left the upstream part of the four beam lines (H2, H4, H6 and H8) in the hall can be seen. The new extension part for the hall is shown on the right part.

Figure 2

3D drawing showing the layout of the EHN1 hall extension housing the two detector prototypes for the NP-02 and NP-04 experiments. The H2 and H4 beam line extensions reaching the two experiments respectively are also visible.

Figure 3

Conceptual layout of the H2/H4 beam line and the newly designed VLE part, leading to the $11\times 11\mathrm{m}$ NP-02/04 cryostat.

Figure 4

Schematic layout of the H2-VLE (top) and H4-VLE (bottom) beam lines, showing the magnetic elements and the proposed beam instrumentation.

Figure 5

3D model layout of the H2-VLE beam line. The quadrupole triplet (in blue) and the target in front of it, are shown in the left of the picture. Part of the NP-02 cryostat is shown in the right of the picture. (Courtesy: V. Clerc and S. Girod)

Figure 6

3D model layout of the H4-VLE beam line. The NP-04 cryostat is shown in the back. The tertiary beam goes from left to right and starts at the secondary target shown at the start of the concrete platform. (Courtesy: V. Clerc and S. Girod)

Figure 7

Optics diagram for the H2-VLE beam line. The red line corresponds to the sinelike ray (particles emerging at 10 mrad from the target), the blue line represents the dispersive ray (at 5%) and the green line the magnification term (corresponding to 1 mm at the origin).

Figure 8

Similar to Fig. 7 for the case of the H4-VLE line.

Figure 9

(a) and (b) The H2 secondary beam profiles at the secondary target, in the horizontal (left) and the vertical (right) planes. (c) and (d) The H4 secondary beam profiles at the secondary target, in the horizontal (left) and the vertical (right) planes.

Figure 10

g4beamline® model of the H2-VLE beam line. The green shapes correspond to the quadrupoles, the red ones in the bending dipoles. The secondary target and acceptance quadrupoles are shown inside the shielding bunker and not visible. The dump absorbing the secondary particles is located next to the field-lens quadrupole (Q24). The model of NP-02 detector is shown on the right. (Courtesy: M. Rosenthal and N. Charitonidis)

Figure 11

VLE beam content at the NP-02 experiment, within the beam pipe aperture, for ${10}^6,80\mathrm{GeV}/c$ pions impinging on the secondary target. g4beamline simulation using the FTFP_BERT physics list.

Figure 12

Momentum bite of the beam for three different collimator slit sizes, for the case of $4\mathrm{GeV}/c$ beam. The full-acceptance momentum spread is 5%.

Figure 13

Reconstructed momentum bite for a $7\mathrm{GeV}/c$ beam, taking into account the material on the beam line (geant4 simulation).