Lasers and Laser Safety’s Role in Accelerator Facilities

Author: Ken Barat, LBNLLawrence Berkeley National Laboratory

HPS Accelerator SectionTAM-F.4

June 29,2010

50th University of laser

2010 is being celebrated as the 50th Anniversary of the invention of the laser.

It has developed from a technology once said to be looking for an application

To a technology that has applications in all aspects of modern society

Laser History Milestones

Einstein – Theory of Stimulated Emission of Radiation. - 1917

Arthur Schawlow and Charles TownesNobel prize for theory on “Optical Maser” based upon this theory of Stimulated Emission. - 1958

Theodore Maiman invented the 1st Laser –made the first laser operate on 16 May 1960 at the Hughes Research Laboratory in California, based upon Schawlow & Townes theory.

Accelerator no longer private domain of Health Physicist

There is a long history of particle physics machines, which continues today The most recent example is the Large Hadron Collider

Today these machines no longer stand alone A variety of Accelerator type facilities exist all around the

world, yielding vital scientific data and findings. Designed to be a multi disciplinary user facility

Three of the more Modern Accelerator types today are:

Synchrotron Facility With additional features, such as controllable polarization

(both linear and circular), laser-like collimation, and pulsed time structure, these characteristics have made synchrotron light sources the x-ray source of choice for a wide range of research

A few examples include:

Shanghai Synchrotron Radiation Facility

Shanghai Synchrotron Radiation Facility, SSRF, is a third-generation of synchrotron radiation light source. Up to now, SSRF is the biggest scientific platform for science research and technology development in China, and more than hundreds of scientists and engineers from universities, institutes and industries in domestic and even overseas can do research, experiments and R&D by using SSRF each day.

Japan – Spring 8

SPring-8 is a synchrotron radiation facility located in Hyōgo Prefecture, Japanand run by the Japan Synchrotron Radiation Research Institute. The machine consists of a storage ring containing an 8 GeV electron beam. The beam is extracted and run through undulators to produce synchrotron radiation with energies ranging from soft X-rays (300 eV) up to hard X-rays (300 keV).

United States

APS- Advanced Photon Source- Argonne Nat Lab, IL NSLS- National Synchrotron Light Source, Brookhaven ,

NY SSRL- Stanford Synchrotron Radiation Lightsource, CA ALS- Advanced Light Source - Lawrence Berkeley Nat

Lab, CA

Free Electron FacilityWith the FEL we have in a femtosecond pulse similar brilliance as a

storage ring delivers in one second, and the means one can study completely complementary aspects. If you want to look at dynamics you also need optical lasers to trigger these effects. So this will be a combination of optical lasers and X-ray lasers. And they will also look at different forms of matter, such as hot, dense matter and study their equation of sate, which will have an impact in plasma physics. But it will also have an impact in understanding matter at elevated temperatures and pressures…..The science you would be doing with an FEL, is very different from the science that you can do with 3rd generation sources.

Interview with Gerhard Materlik, CEO of the Diamond Light Source in the UK, published in 2010 Nature Materials

Another Device that mixes Ionizing and nonionizing radiation

Free Electron Laser

Free Electron LaserFEL

Jefferson Lab is shown

Free Electron Facilities & Accelerators

Can be found around the world

Armenia SwitzerlandAustralia TaiwanBrazil ThailandCanada United KingdomChina (PRC) United StatesDenmark SingaporeFrance South KoreaGermany SpainIndia SwedenItaly NetherlandsJapan RussiaJordan

Desk top accelerator

Coming to a space near you

Optical Accelerator

Now found at about a dozen labs around the world 1 GeV across 3 cm device

Optical Accelerator

1 GeV across 3 cm device Wim Leemans, OASIS Group leader

Laser Plasma Acceleration (LPA)

Intense (1019 W/cm2) laser

Plows through plasma

Creates longitudinal charge oscillation

Results in strong accelerating fields

Compact accelerator

Mm-scale jet Cm-scale capillary

The newest major facility to come on line isLinac Coherent Light Source (LCLS)

SLAC's two-mile-long linear accelerator (or linac) has begun a new phase of its career, with the creation of the Linac Coherent Light Source (LCLS).For more than 40 years, SLAC's linac has produced high-energy electrons for cutting-edge physics experiments. Now, scientists continue this tradition of discovery by using the linac to drive a new kind of laser, creating X-ray pulses of unprecedented brilliance.LCLS produces pulses of X-rays more than a billion times brighter than the most powerful existing sources, the so-called synchrotron sources which are also based on large electron accelerators.

With an eye towards the future

What is coming next?

“Next Generation Light Source”

More readable look

Future Applications of LPA

Coherent VUV FELThere is worldwide interest : in free-electron lasers that give ultrashort pulses of light in the vacuum-ultraviolet region of the spectrum. The electron bunches from the LOASIS GeV laser wakefield accelerator to drive a VUV FEL. This facility would provide scientifically useful light and would also serve as an LBNL testbed for FEL concepts.

Coherent Terahertz Source:THz sources have multiple applications in investigating the properties of matter. The LOASIS LWFA generates THz radiation which is inherently synchronized with the electron bunch and accelerating laser beam pulses.

BELLA = BErkeley Lab Laser Accelerator

Higher laser energy source Longer plasma length (3cm to 1 meter) Higher output- goal 10 Gev beam

BELLA Laser Will Enable 10 GeV Module

< 100 cm1000 TW40 fs

e- beam

~10 GeVLaser

• Accelerator science studies (10 GeV, beam optimization, efficiency etc…)- Positron production; plasma wakefield acceleration

• Applications:- Hyperspectral radiation: coherent THz; X-ray FEL driver; gamma-rays- Detector testing- Non-linear QED

2013 Experiments

A quick word on lasers & laser radiation

Traditionally risk is from line of sight Not 4 Pi lambration exposure pattern Not a contamination concern Laser off, hazard gone No regulatory control on acquiring

Some product safety rules exits-CDRH Limited regulatory control once acquired

A few State programs User Guidance standard US & International versions

Let use the Advanced Light Source as a example

ALS is a third generation light source

Range of experimental and commercial studies at the ALS

Protein Crystallography Chemical Dynamics Environmental studies Lithography inspection New types of Spectrometers New types of microscopes Structurally Integrated Biology for Life Science

New top off mode

ALS has just completed an upgrade to what is called Top Off Mode

Top of mode, yields a constant current to the user. Approximately 500mA

Where laser are found at ALS

Attached to beam lines In experimental hutches that allow the radiation beam to

exit from vacuum to air Full free standing laser labs feeding beam into beam line Use laser to generate femto second x-rays

femtosecond electron bunch

undulatorbeamline

70 ps electronbunch

femtosecondlaser pulse

spatial separationdispersive bend

laser modulation of e-beam energy

femtosecond x-rays

Generation of Femtosecond X-rays from the ALS

A. Zholents and M. Zolotorev, Phys. Rev. Lett., 76, 916 (1996)Schoenlein et al., Science, 287, 2237 (2000)

mirror

femtosecondx-rays

e-beam

laser

slit

bendmagnet

1 2 3

Controlling X-Rays with Light

T.E. Glover, M.P. Hertlein, S.H. Southworth, T.K. Allison, J. van Tilborg, E.P. Kanter, B. Krassig, H.R. Varma, B. Rude, R. Santra, A. Belkacem, and L. Young, "Controlling X-Rays with Light," Nature

Physics (25 October 2009)

So far we have established lasers play a role in accelerator facilities

Where does laser safety come in? The answer, not yet

Majority of accelerator sites service a worldwide user population

With that in mind, one needs to remember safety culture is not uniform across the user spectrum as well as running 24/7

This at times is the unmentioned challenge to the facilities safety staff

Laser Safety OfficerLSO

Whoever takes on the role of LSO is responsible to see that laser safety is addressed

That goes for whenever lasers are used at the Accelerator facility

ANSI standard gives LSO a great deal of flexibility to use professional judgment

Beamline laser work

The majority of laser work at a beam line involves an enclosed laser system.

Meaning that during normal operational runs, it is a safe setup

The safety issue is during initial alignment and system modifications

Safety culture

With 2000 users a year and a home based user core, a strong safety culture is a foundation of laser safety

Laser Safety at the ALS Experimental Summary Sheet (ESS) Annual experimental review Beamline scientist role Strong LSO presence LBNL laser use requirements

Authorization and training On the job training Beam control

Regulatory club DOE~NRC

Shielded Hutches

Shielded hutches primary design is for radiation safety

All interlocked to radiation protection system, some to a laser interlock

Windows are shielded or covered as a laser barrier

User maybe inside with laser on and door closed, synchrotron beam off

Laser beam could be entering or exiting hutch or just contained inside

Hutchesfor radiation protection

Hutch In & Out

Shifting to beamlines

Simpler and smaller

Look from above

Port cover on Beamline

Laser labs on the floor

Soft hutch operates as typical laser lab

Entry way control Warning sign Eyewear Table enclosures Beam blocks Perimeter guards

Beam tube over shielding blocks

Laser Safety at End Station

Laser beam hazard only exists during alignment & or set up

ANSI Z136.1

Overall laser safety controls are based on the American National StandardsZ136.1 Safe Use of Lasers

In 2011 may also have Z136.8 Safe use of laser in the Research , Development and Testing

Environment

Acknowledgements

Author thanks Jim Rockwell, John O’Hagan and others whohave helped him grow as a laser safety advisor. As well theauthor would like to acknowledge the researchers at LawrenceBerkeley National Laboratory and the National IgnitionFacility at Lawrence Livermore National Laboratory whohave added greatly to his knowledge and appreciation of laserusers.

Contact information

For further information and feedback please contact me at

Kbarat@lbl.gov 2 more slides

Time for questions

Follow up information