Extremal double circulant Type II codes over Z4 and construction of 5-(24, 10, 36) designs Original Research Article

In this paper, we provide a classification of extremal double circulant Type II codes of length 24 over Z4. It is shown that the sets of supports of the codewords of Hamming weight 10 in certain extremal Type II codes of length 24 form 5-(24, 10, 36) designs. Designs with these parameters were not previously known to exist. A new extremal Type II double circulant code of length 32 is also constructed.