SLAC Experiment E150 Home Page
SLAC Experiment E150 Home Page
A Plasma Lens Experiment at the Final Focus Test Beam
This experiment - now completed - studied how a high-energy electron beam can be focused
by a small (3 millimeter long) plasma volume, with a plasma density
of 2 to 100 times 10^16 per cubic centimeter.
The electron beam, of an energy of 30 GeV, was delivered by the Final Focus
Test Beam (FFTB) beamline at the end of SLAC's SLC [Stanford Linear Collider].
It was expected that the plasma lens will focus the beam from about
5 micrometer (in absence of plasma lens) to about 2 micrometer.
For more detail, see the proposal or recent publications
(under Publications and Public Documents below).
This experiment had been approved in September 1997. After further design
of the apparatus during 1998,
construction of the apparatus and installation in the
FFTB began in January 1999; the experiment took first data
during summer 1999, in runs in the beginning of July, beginning of August,
and another two weeks at the end of September.
During the year 2000, we had two more runs using positrons,
and one more with the electron beam.
(The theory predicts, that positron beams should be focused as well as electron
beams by a plasma; so we tested this, too.
By reversing the currents in all magnets in the FFTB beamline, this beamline
could also transport and focus positrons.)
This experiment had been proposed and was done by a collaboration
of about 25 physicists from 10 national laboratories and university
groups in the U.S. and Japan
(see list of collaborators below).
News: (latest on top)
(For collaborators only)
The e-mail discussion list for E-150,
(Meeting minutes and announcements for collaborators.
Pushing this button spawns a newsreader program.)
Link to the
SLAC FFTB Home Page and the
Fermilab FFTB Home Page.
List of all publications in Spires with
Plasma Lens or Focus(ing)
in their title
(72 entries today; note also some additional
relevant papers in the reference section of the E150 proposal
[ PDF 1.4MB]).
- (Nov. 30, 2001) "Observation of Plasma Focusing of a 28.5 GeV Positron
Beam" was published in the December 10, 2001 issue of Physical Review
Phys.Rev.Lett. 87, 244801 (2001).
This paper is also featured in an article,
Plasma Puts the Squeeze on
Physical Review Focus,
an American Physical Society Website explaining new results published in
Physical Review to students, researchers in other fields and science
- (Mar.8, 2001) E-150 is featured as one of 8 items in the
'Particle, Nuclear and Plasma Physics' section of the
American Physical Society's
'Physics News in 2000' ( p.6 of a
PDF file, 1MB)
- (Jan. 5, 2001) E-150 is a feature article in the November 2000 CERN
Courier (Vol 40 No 9 p.24-26)
- (October 23, 2000, Jan.5, 22, 2001) Hector Baldis's talk at the
American Physical Society Division of Plasma Physics/International Congress
on Plasma Physics meeting in Quebec City, October 2000,
(available here as a
( HTML Slide Show,
is featured in
the APS's weekly Physics News Update
of Oct. 19, 2000, by P.F.Schewe and Ben Stein (local copy
and in the December 2000 Physics Today (vol. 53 Issue 12 p.9)
- (October 2000) E-150 results were advertised at the
9th Workshop on Advanced Accelerator Concepts. Santa Fe, New Mexico, USA. June
11-16, 2000. and
the 20th International Linac Conference (Linac2000), Monterey, California,
21-25 Aug 2000. (See
E-150 Publications Page for the talks.
- Older News Items are below.
- (June 22,2000) Another run with electron beam and laser beam
coming up, June 26 to July 17, 2000.
- (April 12, 2000)
Run underway (until April 23, 2000) to show focusing of positrons
with the gas jet being ionized by the LLNL laser.
- The March 2000 run showed evidence of focusing of positrons.
(gas jet being ionized by the passing poistron beam).
Results are being analysed.
- (January 17, 2000)
- The data from last year's runs are being analysed; while some
results appear to be quite good, further checks and comparisons
with simulations are needed before publication.
- In this new year, three further runs are planned, two
runs with positrons during
Collaborators, mark your calendars!
- 28 February to 20 March 2000 (3 weeks) and
- 10 April to 24 April 2000 (2 weeks),as well as
- another 3-week run with electrons during June or July 2000.
- (October 5, 1999) The latest run (Sept. 20 - Oct.4, 1999)
ended early Monday morning.
Many data runs with the electron beam self-ionizing the gas, and some
with the laser, have been taken and await analysis.
- (August 6, 1999) (Electron and Laser)Beam for the second run
(Aug.2-Aug.16, 1999) is imminent!
For collaborators, a shift list for the week starting
August 2 (gif, 14k)
August 9 (gif, 17k)
has been prepared by J. Ng.
Also, don't forget the daily operations meeting at 4 p.m. in Bldg. 407!
(Minutes on the mailing list/newsgroup server).
- (July 8, 1999) An image of the laser focus, in the plasma chamber
(filled with air, when picture was taken), just above the
gas jet, in the plane of the electron beam:
jpg , 197kB.
The length is about 3.5 mm, height about 75 micrometer.
(Electron beam would go from right to left).
Now, we only need to get a background-free electron beam focused
to about 5 micron there, with the laser and gas jet firing at the
same time... (Actually, we're getting there)
- (June 30, 1999)More pictures (sideways):
"BSM readied to be lowered into the chamber"
jpg , 209kB,
"going ... going ... where are the gold foils?"
jpg , 203kB,
"It all fits!"
jpg , 204kB.
- (June 29, 1999) Pictures (taken June 29, 1999) of the plasma chamber
installation into the beamline:
"ok guys, easy does it"
jpg , 200kB,
"get in there!"
jpg , 201kB,
"well, the spokesmen are happy, but ..."
jpg , 190kB,
"uh-oh ... will it fit ??"
jpg , 198kB
(Tilt head sideways to view).
- (June 29 , 1999) Run starts this week!
For collaborators, a
updated run plan (gif, 24k)
and a shift list for the week starting
June 28 (gif, 21k)
July 5 (gif, 24k)
has been prepared by J. Ng.
Note that the July 5
shift list posted above
is a NEW version, replacing last week's draft; be sure to check it!
Also the run plan has been updated today (Tuesday, 29-June-1999).
The official shift list is the one on the board in Bldg. 407
(and might reflect some swaps).
There is a daily E-150 operations meeting at 4 p.m. in Bldg. 407.
- (April 26, 1999) Pictures (taken April 22, 1999) of the Plasma Chamber,
which had arrived
at SLAC from Fermilab last week, ahead of schedule:
Curtis Crawford shows off the great work of his colleagues at
jpg , 201kB,
in a top view,
jpg , 193kB.
Now, do you remember what goes into which port?
And will it all fit?
- (April 16, 1999) The Plasma Chamber has been completed at Fermilab
two weeks ahead of
schedule! (It is a complicated vacuum chamber, with ports for the
electron beam to go through, the gas jet, ionizing laser beam,
wire scanner, pumps etc. to go in).
It is expected at SLAC on April 19.
- A Collaboration Meeting was held at SLAC on April 16, 1999.
see Agenda here.
- (March 16, 1999) Pieces of the experiment are coming together;
see these photos taken on 15 March 1999:
Electronics rack in Bldg. 407A
jpg , 207kB;
Gas jet on test stand in Bldg 104,
jpg , 193kB;
Laser table in Bldg. 407B,
jpg , 206kB
(No, the laser isn't on, otherwise, I'd be wearing goggles);
- (January 21, 1999) A Collaboration Meeting has been held at SLAC on January 21, 1999;
see the final
Weekly progress meeting continue to be held Thursdays at 2 p.m.
- (January 15, 1999) The pieces for the ionizing Laser arrived from Rochester on Jan. 14;
the laser is now being reinstalled in Building 407.
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This page was created by
Achim W. Weidemann).
For questions or suggestions regarding this page, please send email to
This page was last modified on November 30, 2001 by
Achim W. Weidemann.(broken links fixed 19-Jan-2004)