Searches for the superheavy hydrogen isotope {sup 7}H in the absorption of stopped {pi}{sup -} mesons

Experimental searches for the superheavy hydrogen isotope {sup 7}H were performed in reactions involving the absorption of stopped {pi}{sup -} mesons on {sup 9}Be and {sup 11}B nuclei. In the reaction {sup 9}Be({pi}{sup -}, pp)X, the missing-mass spectrum shows evidence for the formation of {sup 7}H states, that of E{sub r} = 16 {+-} 1 MeV and {gamma} {approx_equal} 2 MeV and that of E{sub r} = 21 {+-} 1 MeV and {gamma} {approx_equal} 5 MeV (E{sub r} is the resonance energy with respect to breakup into a trition and four neutrons, and {gamma} is the observed level width)