BoNuS Collaboration at Jefferson Lab

Bound (aka "Barely off-shell") Nucleon Structure Collaboration - "BoNuS "

This is the web site of the BoNuS working group. The main purpose of our group is to work on an experiment (E03-012) to study neutron structure by scattering electrons from a deuterium target and detecting a slow-moving recoil "spectator" proton in coincidence. This experiment uses a novel proton recoil detector (a Radial Time Projection Chamber - RTPC - with GEM readout) in the CLAS (CEBAF Large Acceptance Spectrometer in Jefferson Lab's Hall B). The data will extend the recently completed experiment E94-102 ("Electron Scattering from a High Momentum Nucleon in Deuterium" - Summary , full proposal) towards lower spectator momenta (as low as 70 MeV/c). This idea is based on Rolf Ent's and Thia Keppel's "LENT" proposal to measure neutron structure functions in deuterium by tagging a low-momentum, backwards going spectator proton.
Other plans include work on establishing a database on low Q² (between 0 and 5 GeV²) measurements of proton and neutron structure functions, including appropriate parametrizations in the resonance region and at very low Q². Topics of interest include bound nucleon/nuclear structure functions, EMC effect, and duality in nucleons and nuclei.

Link to the RTPC webpage

Status

The BoNuS experiment E03-12 has been run as "run group e8" for Fall of 2005. An engineering run has been completed in June 2005.
Some figures and additional information can be found at a subdirectory with figures. Additional information on the RTPC detector can be found here. Howard Fenker maintains a BoNuS website with extensive material and links.
PAC 23 approved our proposal with an A- rating and 25 days of data taking (+8 days of commissioning and engineering runs). Congratulations to all collaborators.
The Letter of Intent was apparently well received by PAC22. The JLab Theoretical Advisory Committee also had some very nice things to say about the LoI. BoNuS also got mentioned in a JLab On Target newsletter .

Meetings

We meet every week on Wednesdays, 1:30 - 2:30 p.m., in Room A110 CEBAF Center. Off-site participants can join via phone - send requests (with phone number to call) to Vladas Tvaskis. To make slides, documents, figures, tables etc. available to all participants, post them on your private website or, if the information is sensitive, on the secure BoNuS website. Post the link on our Wiki, on your own Wiki page. Also inform Vladas Tvaskis to include any item you want to discuss in the agenda. You can find the agendae and attached minutes of all previous meetings (and the next one coming) on our Wiki!

Past Meetings:

BonusFest 3/11/05

On Friday, March 11 2005, we had an extended "Bonus Physics Fest" meeting, beginning at 10:30 a.m. in Room A110 CEBAF Center. The talks can be found in this directory.

Proposal organization meeting July 16, 2002 See minutes .

Tuesday, May 14 (immediately preceding the "Exclusive Processes" workshop at Jefferson Lab).

Report from Silvano Simula (presented by Mauro Taiuti)
Proposal from the Genova group
Status of 11 GeV CDR contribution
Simulations
Plans for LOI , organization, work distribution

Meeting on April 16, 2002

Wally Melnitchouk presented the Physics background and relevant constraints for the planned experiment. His slides are here . Rolf Ent gave an overview on the present status of the detector design and run parameters. His slides are here .

BoNuS listserve mailer

All announcements of meetings, important information and discussion relating to the BoNuS collaboration will be conducted via the JLab email list server. The list name is BoNuS. The list is not moderated, but you have to be a subscriber to either receive or post messages!

Subscribe to the BoNuS email list!
Send message to all BoNuS collaborators.

Important note: To avoid excessive unwanted email traffic ("spam"), this list (like most JLab email lists) is only open to posting by subscribers. You have to send your post from the same computer (i.e., your "From: " address must be the same) as the one with which you subscribed (the list server is too "dumb" to recognize "similar" addresses or names). To find out under which account/email address you are subscribed, send email to majordomo@jlab.org with a single line in the message body (not the subject): "who bonus ". This lists all subscribers with their actual email addresses used to subscribe. If you want to change your subscription information, click on the link "Subscribe" above for instructions. You might want to remove your old address (to avoid multiple messages each time someone posts to the list) as well as subscribe with a new one. Alternatively, leave the subscription information as it is, but make sure you use the same computer you originally subscribed from to send your post. If you use a pop-mail server etc. like Outlook or Netscape or Pegasys etc., you can specify in your "preferences" what your "From: " (= "email") address should be. Again, make it the same as your subscription address.
If you submit a message to the list with the wrong originating email address/"From:" address, it will BOUNCE. Only the list owner ( Sebastian Kuhn ) but not you will be notified if an email bounces (this is maybe a flaw of the present system). I will try to inform you right away if this happens, but you will have to resubmit the message properly (I will only do this for you in cases of great urgency). Also, to be sure, it is always good to check whether you received your own posting within a few minutes - if not, it likely bounced.

Additional Links of Interest for BoNuS collaborators:

Here is a subdirectory with figures.
Mirror of the present content of our CVS tree for the proposal (for off-site collaborators).
Hall C's collection of Structure Function data and models in the resonance region
DVCS solenoid design studies from Michel Garcon and Cole Smith
A Website exclusively dedicated to the RTPC detector

This site is under construction. More links will be added as they become available - please contact Sebastian Kuhn if you have suggestions for useful links or additions to this page.

Go to the Hall B Website .

Go to the Hall C Website .