2 USC 72a1e - Assistance to Senators with committee memberships by employees in office of Senator

(1) Designation 
A Senator may designate employees in his office to assist him in connection with his membership on committees of the Senate. An employee may be designated with respect to only one committee.
(2) Certification; professional staff privileges 
An employee designated by a Senator under this section shall be certified by him to the chairman and ranking minority member of the committee with respect to which such designation is made. Such employee shall be accorded all privileges of a professional staff member (whether permanent or investigatory) of such committee including access to all committee sessions and files, except that any such committee may restrict access to its sessions to one staff member per Senator at a time and require, if classified material is being handled or discussed, that any staff member possess the appropriate security clearance before being allowed access to such material or to discussion of it. Nothing contained in this paragraph shall be construed to prohibit a committee from adopting policies and practices with respect to the application of this section which are similar to the policies and practices adopted with respect to the application of section 705(c)(1)1 of Senate Resolution 4, 95th Congress, and section 72a–1d (c)(1)1 of this title.
(3) Termination 
A Senator shall notify the chairman and ranking minority member of a committee whenever a designation of an employee under this section with respect to such committee is terminated.
[1] See References in Text note below.