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The reaction ${n} {p} \to {p} {p} \pi^{-}$ from threshold up to 570 MeV

Daum, M. ; Finger, M. ; Finger, Michael, Jr. ; et al.

Eur.Phys.J.C 23 (2002) 43-59, 2002.

Inspire Record 561221 DOI 10.17182/hepdata.43221

The reaction ${n} {p} \to {p} {p} \pi^{-}$ has been studied in a kinematically complete measurement with a large acceptance time-of-flight spectrometer for incident neutron energies between threshold and 570 MeV. The proton-proton invariant mass distributions show a strong enhancement due to the pp($^{1}{S}_{0}$) final state interaction. A large anisotropy was found in the pion angular distributions in contrast to the reaction ${p}{p} \to {p}{p} \pi^{0}$. At small energies, a large forward/backward asymmetry has been observed. From the measured integrated cross section $\sigma({n}{p} \to {\rm p}{p} \pi^{-})$, the isoscalar cross section $\sigma_{01}$ has been extracted. Its energy dependence indicates that mainly partial waves with Sp final states contribute. Note: Due to a coding error, the differential cross sections ${d \sigma}/{d M_{pp}}$ as shown in Fig. 9 are too small by a factor of two, and inn Table 3 the differential cross sections ${d \sigma}/{d \Omega_{\pi}^{*}}$ are too large by a factor of $10/2\pi$. The integrated cross sections and all conclusions remain unchanged. A corresponding erratum has been submitted and accepted by European Physics Journal.

4 data tables

Table 1

Differential cross sections DSIG/DOMEGA for excusive PI- production in N P interactions at incident kinetic energies 315, 345 and 375 Mev after background subtraction and efficiency correction.

Table 2

Differential cross sections DSIG/DOMEGA for exclusive PI- production in N Pinteractions at incident kinetic energies 405, 435 and 465 Mev after background subtraction and efficiency correction.

Table 3

Differential cross sections DSIG/DOMEGA for exclusive PI- production in N Pinteractions at incident kinetic energies 495, 525 and 550 Mev after background subtraction and efficiency correction.

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