Measurement of the production of charged pions by protons on a tantalum target

Comments on “Measurement of the production of charged pions by protons on a tantalum target”

“…To a good approximation, these dynamic track distortions increase linearly with time in the spill 1 . Their size in the r · φ coordinate typically reaches 15 mm, at small radius, at the end of the spill.…”

“…The larger part of the HARP Collaboration (hereafter referred to as 'authors') published in this journal an article (hereafter referred to as 'article') entitled 'Measurement of the production of charged pions by protons on a tantalum target' [1]. This article has not been signed by us, also members of the HARP Collaboration, because we feel unable to take responsibility for the reported results.…”

Cross sections of large-angle hadron production in proton– and pion–nucleus interactions III: tantalum nuclei and beam momenta from ±3 GeV/c to ±15 GeV/c

“…These problems, together with others that affect the HARP Collaboration's data analysis, are discussed in detail in [15][16][17] and summarized in the appendix of [1]. We hold that the tantalum results published by the HARP Collaboration [14,18] are not suitable for the optimization of the proton driver of a neutrino factory. …”

Comments on TPC and RPC calibrations reported by the HARP collaboration

“…[7]- [9]), the authors fit the distorted track together with the undistorted beam point. The beam point is assigned a weight 'similar to a TPC hit' [7] which implies that the beam point's error is constant and not what it must be: the convolution of the errors of two extrapolations to the interaction vertex, of the beam particle's trajectory and of the secondary track's trajectory. Primarily because of the momentum-dependence of multiple scattering, the correct error of the beam point varies considerably for different beam momenta and from track to track.…”