The researchers at Institute of Modern Physics, Chinese Academy of Sciences (IMP) have investigated the proton- and ³He-induced reactions on a ¹⁹⁷Au target at beam energies of 2.8, 5, 10, and 16.587 GeV/nucleon, and found that the 3He-induced reactions give about five times larger cross sections of pion productions than those in the proton-induced reactions. And more importantly, pion production from the ³He-induced reaction is more inclined to low-angle emission. Neutrino production via positively charged pion decay is also discussed accordingly.

Neutrino physics is a hot topic in today’s particle physics. Researchers at IMP investigated neutrino production based on the linear accelerator. Fig.1 shows the inclusive differential cross sections of pion production from the p + Au at an incident beam momentum of 17.5 GeV/c. The results show that for both π- and π+, the calculations fit the E910 data very well, especially at higher momenta. Pion production of the p + Cu reaction at incident beam momenta of 12.3 and 17.5 GeV/c also fits the E910 data very well. From Fig.1, it is also proved that the cross sections at small angles (0.9 <cosθ < 1) are evidently larger than those at large angles, especially for energetic pion mesons. Because the energy distributions of the emitting neutrinos are important for neutrino-nucleus experiments, the researchers also plot the energy distributions of the produced neutrinos at small and large angles as shown in Fig.2. The findings indicate that the produced neutrinos possess different energies from about 1 to 1000 MeV or more. The most probable energy is about 30 to 70 MeV at several GeV incident beam energies. Moreover, neutrinos at small angles possess more energy than those at large angles.

The study of neutrino production based on the proton-linear accelerator is of great significance to the neutrino physics experiments plan.

The work has been published in PHYSICAL REVIEW C 85, 024911(2012)

Weblink: http://link.aps.org/doi/10.1103/PhysRevC.85.024911

Fig.1 Production cross sections of π- (left panel) and π+ (right panel) from the p + Au at the incident beam momentum of 17.5 GeV/c (Ebeam ~16.587 GeV/nucleon) shown in bins of cosθ (relative to beam direction). Numbers in the legend refer to the center of each bin. (Imaged by IMP)

Fig.2 Energy distributions of neutrino produced at angles 0.9 < cosθ < 1 and 0.5 < cosθ < 0.6 from positively charged pion decay in the P+ Au and 3He + Au reactions at incident beam energies of 2.8 and 10 GeV/nucleon. (Imaged by IMP)