Any administrative law judge, in the state service as such administrative law judge twenty or more years in the aggregate, who leaves such service because of failure of reappointment, or because of abolition of his position, shall, during the remainder of his life, receive an annual pension payable from the General Fund equal to fifty per cent of his average annual salary for the five years next preceding his retirement. The administrative law judges may continue to contribute to the State Employees Retirement Fund and shall be entitled to general retirement rights under chapter 66. The acceptance of the pension herein provided for shall be in lieu of all benefits under the State Employees Retirement Act, and any administrative law judge accepting a pension under this section shall not be entitled to the return of any payments made by him to the State Employees Retirement Fund.