Rawson is undergoing the concussion protocol after a clash of heads during last week’s defeat at Swindon saw him taken to hospital as a precaution.
Cooper has brought in six players during the January transfer window and hopes to sign up to three more before the end of the month.
However,Callum Evans and Fabien Robert have been loaned out until the end of the season to Macclesfield and Aldershot respectively.
David Amoo is absent for Cambridge with a further hamstring problem.
Midfielder Amoo came on as a substitute in last weekend’s goalless draw with Mansfield, but was replaced himself after 10 minutes.
Striker Jabo Ibehre is available following the completion of his three-match suspension.
England manager Gareth Southgate has claimed that the country needs to boot racism out of its own football before criticising World Cup hosts Russia.
Newcastle have been linked with a shock move for former Sunderland goalkeeper Simon Mignolet during the summer.