The Advanced Photon Source
a U.S. Department of Energy Office of Science User Facility

APS UEC Bylaws

The Advanced Photon Source Users' Executive Committee Bylaws  

This set of bylaws defines the membership, responsibilities, structure, and function of the Advanced Photon Source Users' Executive Committee (APS UEC).


The Advanced Photon Source Users' Executive Committee (APS UEC) is responsible for advising the Associate Laboratory Director (ALD) for Photon Sciences in the following areas:

  • The Committee will serve as an advocacy group for the Advanced Photon Source (APS) user community and the APS facility.
  • The Committee will provide advice to the ALD on matters affecting the user community.
  • The Committee will assure good communication between the APS user community and the APS management.

Users' Organization Membership

Membership is automatically granted to all badged users of the Advanced Photon Source.

Users' Executive Committee (UEC)

The UEC is charged with conducting the business of the APS Users' Organization. In general, the UEC shall have up to 13 regular members, consisting of the Chair, Vice Chair, Past Chair, and up to 10 other regular members. The regular members of the Committee must not be a current member of the APS staff. Each regular member has a three-year term, except for the Past Chair who may have up to a four-year term on the Committee. Committee members may be re-elected. The Committee shall also include a position for a graduate student or postdoctoral fellow, if elected within two years of completing Ph.D. This position shall have a two-year term. All committee members are voting positions.

Four members shall be elected by the APS Users' Organization members each year, except in years when the student/postdoctoral fellow position is being filled, when up to five members may be elected. In case of resignation, death, or disability of a Committee member, a replacement will be appointed by the Committee to complete the term: the candidate from the immediately preceding election slate who received the highest number of votes but was not elected.  This appointed member may stand for re-election.

Committee members will be elected to the APS Users' Executive Committee through an electronic voting procedure conducted at the time of the annual Users Meeting. The open election period shall precede the Users Meeting by no less than two weeks and will close at the Users Meeting. All APS Users' Organization members are eligible to vote. 

The Committee is responsible for facilitating a slate of candidates via a call for nominees and providing advance notice of the election to the APS Users' Organization membership. Any APS Users' Organization member may nominate candidates or self-nominate. Candidates must be APS Users' Organization members at the time of election. The candidates shall possess the highest personal and professional ethics, integrity, and values, and be committed to representing the interests of APS Users' Organization and APS mission and values. The candidates must be willing to devote sufficient time to fulfilling their duties and responsibilities, shall they be elected.

To promote representation of smaller interest groups, a weighted system of voting shall be used. Each ballot may select the number of candidates that equals to the number of expected vacancies, with the first choice assigned a number that equals to the number of expected vacancies, the second choice assigned a number that equals to the number of expected vacancies minus one, and so on. Tie votes shall be decided by a coin toss.

Student/postdoc member shall be elected in conjunction with the regular member election as needed.


The officers of the APS Users' Executive Committee shall include.

  1. The Chair: The Chair shall serve for one year and enforce due observance of the rules and perform duties as directed by the Committee and as the office may require. To assure continuity, the Chair shall continue to serve on the Committee as Past Chair for a subsequent one-year term in an advisory role to the current Chair. If the Past Chair has already finished a three-year term, the Past Chair will remain as a voting member of the Committee until the following Users Meeting.
  2. The Vice Chair: The Vice Chair shall serve for one year and be elected by the voting members of the Committee after the Users Meeting. The Vice Chair shall be responsible for organizing the scientific program for the next Users Meeting. At that Users Meeting, the Vice-Chair will become the Chair. The Vice Chair shall stand in for the Chair if the Chair is unavailable.

Officers' terms on the Committee shall be extended as needed to perform the above services.


Should the Chair resign, the current Vice Chair shall assume the responsibility of Chair for the remainder of the term, and then serve in the normal sequence of succession. The Committee shall elect a replacement for Vice Chair. Any other vacancy on the Committee shall be filled following procedures specified in the Users' Executive Committee section of APS UEC Bylaws.



  1. The APS UEC, in collaboration with Photon Sciences Directorate, shall organize an annual Users Meeting. The APS Users' Executive Committee shall be responsible for the programs of the Users Meetings. APS User's Organization members shall receive appropriate advance notice of the Users Meetings.
  2. The APS Users' Executive Committee shall meet at intervals of approximately three months, with no fewer than four regular meetings per year, one of them in combination with the Users Meeting. Argonne National Laboratory will be responsible for providing administrative and financial support for these regular meetings as needed.
  3. Additional APS Users' Executive Committee meetings may be called at the Chair’s discretion or by a majority of the APS UEC.
  4. Announcement of all meetings shall be made in advance to all APS UEC members.
  5. Minutes of all APS UEC meetings shall be recorded by the User Office Liaison present. After approval by the APS UEC, the minutes shall be made available to members of APS Users' Organization upon request. 
  6. The APS UEC shall be responsible for collecting nominations for APS UEC Awards and selecting the Awardees.


A quorum of the APS UEC requires the presence of at least half of the members, which must include either the Chair or Vice-Chair or both. Issues are voted upon and decided by the majority of the members present. In case of a tie, the Chair has the deciding vote.


Proposed changes to the Bylaws shall be presented by the Committee to the APS Users' Organization membership with facility access approval within the past 5 years, who will cast votes through electronic means. An open voting period of no less than two weeks is required. These bylaws shall be amended by a favorable vote of two-thirds of ballots cast.

  • Revision 5
  • Adopted February 8, 2021
  • Fan Zhang, Chair, APSUO

To comment on the contents, please contact or 630-252-9090.