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Two independent methods: ANC (Asymptotic normalization coefficients) [1,2] and MDM (Modified diffraction model) [3,4] were applied to new and existing experimental data. The purpose of this analysis is search for states with enhanced radii in isobar-analog excited states of triplet A=12: $^{12}$B – $^{12}$C – $^{12}$N.
There is experimental work [1] where halo was observed for 2 states of $^{12}$B: 2¯, 1.67 MeV and 1¯, 2.62 MeV. To check this result new experimental data $^{11}$B(d,p)$^{12}$B was obtained at E$_{d}$ = 21.5 MeV [5,6]. On base of ANC analysis of this new data [5,6], neutron halo existence was confirmed for the 2¯, 1.67 MeV and 1¯, 2.62 MeV states in $^{12}$B. An unexpected result was obtained for the unbound 3¯, 3.39 MeV state, which is 19 keV above the neutron emission threshold. Its halo radius was also found to be increased and equal to ~ 6.5 fm [5,6]. This result can be considered as an evidence of the halo-like structure in this $^{12}$B state.
What can we expect in isobar-analog states in $^{12}$C and $^{12}$N? Are these states also characterized by enhanced radii? To check this prediction, preliminary analysis of existing $^{12}$C($^{3}$He,t)$^{12}$N and $^{12}$C($^{3}$He,$^{3}$He’)$^{12}$C experimental data using Modified diffraction model (MDM, [3,4]) was done.
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