i've read somewhere (can't recall) that nirodha samapatti (ninth jhana) can be experienced with access concentration and that the jhanas are not entirely necessary for this to occur.
i believe the first time one experiences nirodha samapatti it may be sudden and last but a few mind moments, i read that this is called GLIMPSING nibbana
when the mind starts again and the senses come back on-line this person is sotapanna (the lowest degree of saints) 3 fetters have been extinguished identity view, doubt, clinging to rites and rituals.
does this agree with anything you may have read previously