The production cross section of $30.92\mathrm{GeV}/c$ protons on carbon is measured by the NA61/SHINE spectrometer at the CERN Super Proton Synchrotron by means of beam attenuation in a copy (replica) of the 90-cm-long target of the T2K neutrino oscillation experiment. The employed method for direct production cross-section estimation minimizes model corrections for elastic and quasielastic interactions. The obtained production cross section is ${\sigma }_{\mathrm{prod}}=227.6\pm 0.8{(\mathrm{stat})}_{-3.2}^{+1.9}(\mathrm{sys})-0.8(\text{mod})\mathrm{mb}$. It is in agreement with previous NA61/SHINE results obtained with a thin carbon target, while providing improved precision with a total fractional uncertainty of less than 2%. This direct measurement will reduce the uncertainty of the T2K neutrino flux prediction.

• Received 27 October 2020
• Accepted 11 December 2020

DOI:https://doi.org/10.1103/PhysRevD.103.012006

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Published by the American Physical Society