Section 60E. In any civil action for malpractice, error or mistake against a provider of health care where an impartial medical examination has not been ordered at a hearing under the provisions of section sixty B, the presiding justice at a trial may upon the application of either party or upon his own decision appoint an impartial and qualified physician or surgeon or other related professional person or expert to conduct any necessary professional or expert examination of the claimant or relevant evidentiary matter and to report to or testify as a witness thereto. Such a witness shall be allowed traveling expenses and a reasonable fee to be fixed by said justice.