What Is Sirepo? Software & Science Codes Overview

In high energy physics, accelerator physics, and other science disciplines, simulation codes are a vital tool in the research arsenal. The codes often run through the command line, use specialized input files, and sometimes have their own build system.

Learning how to use these codes is hard and can take weeks or months. This means that despite being very useful, many of these codes have only a handful of expert users.

Sirepo was built to bring that kind of scientific computing to the cloud. It’s a gateway for those science codes to be used on a browser, to be accessed via graphical user interface (GUI). By wrapping these codes in GUIs and maintaining them on the backend, we provide a place for scientists to focus on their physics over IT and CS issues.

But even if you’re familiar with codes for accelerators or X-ray beamlines, you might still be thinking, what exactly is Sirepo?

We’ve put together this bird’s-eye view of Sirepo to answer that. Think of it as your crash-course.

In it, we’ll cover how Sirepo relates to various science codes (elegant, WARP, SRW, etc.); how it can help make running simulations easier; how you can share your models with colleagues; and more. Feel free to skip around, or if you want to see Sirepo in action, check out the tutorial video at the bottom of this article.

Want to jump ahead? Here’s where we’re going

What is Sirepo?

Sirepo is a digital cloud-based framework for running simulation codes in your browser. It is the software that houses the simulation code, which is why we call it a scientific gateway.

Under the umbrella of Sirepo are a number of apps. These are the codes that Sirepo supports with graphical user interfaces you can access via web browser. These apps all share a similar visual language and interface, making it easy for users to switch between different codes.

Take the popular physics simulation code elegant. Sirepo/elegant is an app that runs elegant in your browser without you having to download, install, or keep the code up-to-date. Through Sirepo, elegant is prepackaged and ready to be used.

We at RadiaSoft believe that science is made better by the free flow of information and tools.  That’s why we built Sirepo in the first place, to aid the accelerator community. Therefore, like the codes it supports, Sirepo is open-source.

Simulation codes running on Sirepo

The physics codes Sirepo currently supports fall into three families: codes for particle accelerators, codes for X-ray optics, and codes with electrostatic PIC capabilities.

The library of supported codes on Sirepo is always expanding. Below we’ll get into a few of the most popular codes and what they do to give you an idea of how versatile the Sirepo gateway can be.

elegant

This is a particle accelerator code for electron linacs, synchrotrons, and much more.

According to its user manual, “elegant stands for ‘ELEctron Generation ANd Tracking,’ a somewhat out-of-date description of a fully 6D accelerator program that now does much more than generate particle distributions and track them. elegant, written entirely in the C programming language, uses a variant of the MAD input format to describe accelerators, which may be either transport lines, circular machines, or a combination thereof. Program execution is driven by commands in a namelist format.”

SRW

Its full name is Synchrotron Radiation Workshop and it’s an X-ray optics code for synchrotron radiation and coherent X-ray beamlines, such as what you find at the ALS or NSLS-II.

“Frequency-domain near-field methods are used for the SR calculation, and the Fourier-optics based approach is generally used for the wavefront propagation simulation.

“The code enables both fully- and partially-coherent radiation propagation simulations in steady-state and in frequency-/time-dependent regimes. Besides the SR applications, the code can be efficiently used for various simulations involving conventional lasers and other sources. SRW versions interfaced to Python and to IGOR Pro (WaveMetrics), as well as cross-platform library with C API, are available,”according to its GitHub repo.

OPAL

OPAL or “Object Oriented Parallel Accelerator Library” is a particle accelerator code for linacs and electron guns with 3D space charge. OPAL is open-source and you can learn more about it here.

Synergia

This is a particle accelerator code for single or multiple bunch rings with 3D PIC. It’s a hybrid Python/C++ package. Learn more about Synergia here.

Zgoubi

Originally developed in the 1970s, Zgoubi is a particle accelerator code for electron and ion spin dynamics in rings. Learn more about Zgoubi here.

Imports/exports

Sirepo is designed to aid both the beginner and advanced coder. While a GUI interface is beneficial in many ways, there may be operations and tasks a researcher wishes to carry out in the command line.

This is why there are easy exports to other file formats, like a simple zipped file or Python source file. (Accessible from the top menu bar in your workspace, pictured here.)

Similarly, one can import full lattice files for whichever accelerator they wish to model.

Making collaboration easy

Sharing and collaboration is not so smooth when done in the command line. First, software versions must be the same across all instances, or unexpected input file bugs can appear. Second, the files must all reach their destination intact and in full.

This sounds easy, but is harder to do in practice. And any mistakes mean a wrinkle in results or make a simulation impossible to reproduce.

Great science thrives in collaboration. Unlike traditional command line codes, a simulation in Sirepo is easy to share via link sharing.

Every simulation you create in Sirepo has a unique sharing URL, available in the top menu. Simply copy it and send to whomever you wish, and they will have access to an exact copy. It’s as easy as sending an email or a Slack message.

One thing to note is that Sirepo URL sharing is not like Google Docs. The link you share provides the recipient with a separate copy, not access to the original simulation. This way, you don’t have to worry about anyone altering your simulation.

A walkthrough of Sirepo

It’s important to remember that Sirepo itself is just the container for the codes above and others. Its features change with the codes’ own capabilities. But no matter which one you use, the interface will stay the same.

That said, the best way to understand Sirepo is to see it for yourself.

We recommend this video tutorial of how to build a FODO cell in elegant:

Further resources

More specific information, we have a number of resources available.

• Webinars and tutorials on our YouTube channel
• Help articles on the Sirepo GitHub wiki
• The RadiaSoft blog

Check out Sirepo for yourself today. Sirepo Basic is free to use.

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Accelerator & Beam Physics News: Aug–Sept 2020 Roundup

With all the news coming out of the varied worlds of accelerator and beam physics, and the research and industry applications they fuel, we’re putting together monthly news recaps to show you what you’ve missed.

As summer comes to a close, Fermilab has been chosen to lead one of the National Quantum Information Science Research Centers and SLAC scientists invent low-cost ventilators for COVID use, plus PPPL gains funding to advance diagnostics from DOE. Read on to get more on these stories and others.

Here’s what you should know:

Fermilab to lead $115 million National Quantum Information Science Research Center from Fermilab.

“The U.S. Department of Energy’s Fermilab has been selected to lead one of five national centers to bring about transformational advances in quantum information science as a part of the U.S. National Quantum Initiative, announced the White House Office of Science and Technology Policy, the National Science Foundation and the U.S. Department of Energy today. . . .”

SLAC scientists invent low-cost emergency ventilator and share the design for free from SLAC National Accelerator Laboratory

“Menlo Park, Calif. — Researchers at the Department of Energy’s SLAC National Accelerator Laboratory have invented an emergency ventilator that could help save the lives of patients suffering from COVID-19, the disease caused by novel coronavirus SARS-CoV-2. Using standard parts that cost less than $400, the ventilator could be an affordable option when more sophisticated technology is not available, in short supply or too expensive. . . .”

Next-Generation Electron Source Hits the Bullseye for Materials Studies from DOE Office of Science

“This novel lens design will enable the next generation of ultrafast electron sources. These sources will in turn enable new characterization of materials and molecules. They will fill the gap in spatial resolution between static and ultrafast sources. This ability will allow scientists to characterize chemical dynamics at nanoscale dimensions of billionths of a meter. . . .”

Controlling Light to Accelerate Electrons in Just Meters from DOE Office of Science

“Particle accelerators work by accelerating charged particles, such as protons or electrons, at speeds close to the speed of light. They then smash those particles into a target or other particles. High energy physicists study the particles and radiation released in these collisions. However, conventional radiofrequency accelerators are close to the limits of how much energy they can push to particles. Researchers are developing advanced accelerator concepts to reach new energy levels. The flying focus technology could transform accelerators. Because the new concept needs much less space, future accelerators could be many times smaller than the accelerators of today. . . .”

Check out our blog for more news and articles.

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Accelerator & Beam Physics News: June–July 2020 Roundup

With all the news coming out of the varied worlds of accelerator and beam physics, and the research and industry applications they fuel, we’re putting together monthly news recaps to show you what you’ve missed.

In recent weeks, CMS scientists published their thousandth peer-reviewed paper, CERN makes a push to build the 100km High-Luminosity LHC, the RHIC reaches a 20-year milestone for colliding, and more.

Here’s what you should know:

CMS collaboration publishes 1,000th paper from Fermilab Newsroom

“The discovery of the Higgs particle by the international CMS and ATLAS collaborations is the most famous discovery made to date at the Large Hadron Collider at CERN. The scientists made the announcement on July 4, 2012, and it was later recognized with a Nobel Prize: The theorists who predicted the Higgs mechanism received the award in 2013. . . .”

Running with the Speed of Science in the Race Against COVID-19 from DOE

“[S]cientists are studying three different types of problems: using simulations to understand the protein structure of the virus and how it attacks, utilizing artificial intelligence to identify effective countermeasures against the virus and accelerate the discovery of promising treatments, and working with policymakers to manage the course of the infection and deploy resources strategically. . . .”

Celebrating 20 Years of Smashing Success at RHIC from Brookhaven National Laboratory Newsroom

“Even in a time before Instagram, physicists starting up the Relativistic Heavy Ion Collider (RHIC)—a particle collider at the U.S. Department of Energy’s Brookhaven National Laboratory—knew they needed a great picture to share their success. They and the rest of the world were not disappointed. Around 9 p.m. on June 12, 2000—20 years ago today—subatomic “fireworks” lit up display monitors in the control room of RHIC’s STAR detector . . .”

CERN makes bold push to build €21-billion supercollider from Nature

“CERN has taken a major step towards building a 100-kilometre circular supercollider to push the frontier of high-energy physics. The decision was unanimously endorsed by the CERN Council, the organization’s governing body, on 19 June, following the plan’s approval by an independent panel in March. Europe’s pre-eminent particle-physics organization will need global help to fund the project, which is expected to cost at least €21 billion (US$24 billion) and would be a follow-up to the lab’s famed Large Hadron Collider (LHC). . . .”

Looping X-rays to produce higher quality laser pulses from SLAC National Accelerator Laboratory

“Ever since 1960, when Theodore Maiman built the world’s first infrared laser, physicists dreamed of producing X-ray laser pulses that are capable of probing the ultrashort and ultrafast scales of atoms and molecules. This dream was finally realized in 2009, when the world’s first hard X-ray free-electron laser (XFEL), the Linac Coherent Light Source (LCLS) at the Department of Energy’s SLAC National Accelerator Laboratory, produced its first light. . . .”

Check out our blog for more news and articles.

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Synchrotron Radiation 101: How Light Sources Work and Their Applications

When a beam of electrons traveling close to light speed is bent away from a straight trajectory, it gives off a special kind of light is called synchrotron radiation. Created by particle accelerators called synchrotrons, this kind of electromagnetic radiation has proved to be an incredible scientific tool for investigating matter, the universe, and so much more. In this post, we’re exploring what synchrotron light is, how it’s produced, what it’s used for, and more.

How synchrotrons became light sources

First built in the 1940s, synchrotrons were not originally made to produce synchrotron light. As a type of circular particle accelerator, they were intended to study particle collisions and interactions. But it didn’t take scientists long to notice the synchrotron’s byproduct, an extremely bright light.

Called synchrotron radiation or synchrotron light, it can cover the full electromagnetic spectrum. It’s characterized “by high brightness—many orders of magnitude brighter than conventional sources—and [is highly polarized], tunable, collimated (consisting of almost parallel rays) and concentrated over a small area,” according to IOP. More specifically, the power radiated from this beam is equal to(q²a²/c³), where a is the acceleration and q is the charge. This equation is called the Larmour formula, and it applies to radiation produced from both bending magnets with a circular trajectory and to undulators/wigglers, where the electrons oscillate back and forth. (Natural sources of synchrotron radiation also exist in the universe. The Crab Nebula is one. But as you can imagine, it’s not useful for laboratory experiments. Though, it does tell us a lot about the plasma environment of space.) It took more a decade after that first synchrotron was built, in 1956, for the first dedicated light source experiment to be carried out: an X-ray spectroscopy study by American scientists Diran Tomboulian and Paul Hartman. This happened at Cornell University’s accelerator when synchrotron light was directed off the accelerator ring towards an experimental station. For more than 20 years, scientists utilized this synchrotron “byproduct” for their own work, while the machines themselves were primarily used for high-energy particle collisions. It was not until 1980 that the first dedicated light source facility was built in the United Kingdom at Daresbury. Today, there are dozens in use around the world.

Light source setup

Particle accelerators are what create artificial synchrotron light, but we’re not going to cover those in detail here. (For the full rundown, see our previous post.) Instead, we will give a brief primer on some components unique to dedicated synchrotron radiation facilities.

Storage rings

These specialized facilities use storage rings to produce synchrotron radiation. Storage rings are exactly what they sound like: circular accelerators where electron beams can be stored and kept moving for many hours. In fact, storage rings are synchrotrons. Unlike traditional ones that accelerate particles from low to high energies using radiofrequency (RF) cavities, however, these maintain beam energies and the RF cavities only replace energy lost during circulation.

Beamlines

As the electrons are circulating at the desired energy, they give off light. The direction this light moves depends on your frame of reference. In the laboratory frame, it travels in the same direction as the beam (with an opening angle of 1/ γ, where gamma is the relativistic time dilation factor); in the electron beam frame, it travels perpendicularly to the beam’s path. No matter the frame, that light is allowed to escape the storage ring through ports leading to straight beamlines, which then end in experimental stations (pictured above). The available spectrum of this light depends on two things: (1) the beam’s energy and (2) the properties of the magnetic source (i.e. whether a bending magnet or an undulator or wiggler is being used). In practice, this means higher energy electrons allow for shorter wavelengths. Typically, only a specific wavelength is desired for experimental use. In order to isolate it, a few mechanisms are used to condition the beam as it heads toward an experiment station. One such tool is the monochromator. It “selects” a single wavelength of electromagnetic radiation with a narrow bandwidth. For picking out X-rays, a crystal monochromator is used; for UV light, a grating monochromator is used. Slits control the physical width of the beam and the angular spread. Mirrors and lenses are used as focusing elements. After the light is filtered and focused while traveling down the beamline, it strikes a sample.

Samples

“Sample” is a generic way of referring to the thing a scientist is researching using synchrotron light. It could be a crystal whose structure we wish to better understand. It could be some material or object that we want to image in high resolution. The possibilities are numerous, and we’ll explore some research topics further down. Using the light source, experimental samples are subjected to varying temperatures, pressures, etc. Detectors nearby record the data from the sample-light interaction and send it to computers for collection and analysis.

Types of synchrotron light experiments

What kind of experiments can be done using synchrotron light? Experiments themselves are too numerous to list, but the methods are a little easier to pin down by category. Here are three of the most common.

1.    Diffraction

This happens when synchrotron light is diffracted by the sample itself. Waves (in our case, light waves) are spread out as they pass an object or go through an aperture. After interacting with the sample, that light creates an image, called a diffraction pattern. One can learn more about the sample’s nature by studying this image, e.g. an X-ray image.

2.    Spectroscopy

This happens when light is sent through a sample and measurements are taken on the other side to see which wavelengths are absorbed and/or emitted according to the sample’s characteristics. Spectroscopy gives us a look into the sample’s electrical states or chemical bonds, in addition to its composition.

3.    Imaging

Using X-rays as our wavelength in this example, the light penetrates the sample and emerges on the other side, creating a contrast image of the sample’s interior. It’s similar to how doctors view a broken bone inside your arm with a hospital X-ray machine, except much more powerfully and with a much higher spatial resolution thanks to better focusing.

Industry and research applications

From investigating the structure of crystals and proteins to monitoring air pollution, synchrotron radiation is capable of shedding light on the molecular and atomic worlds. Here are a few ways both industry and research use it in practice.

Medical and pharmaceutical research

Perhaps one of the best-known applications of synchrotron light is in medical and pharmaceutical research. The high intensity of this light allows for the study of disease mechanisms, high-resolution imaging, and advances in microbiology and cancer radiation therapy.

Materials research

One of the advantages of synchrotron light for materials research is its high tunability. Particularly in the X-ray range, scientists can pick and choose exactly what kind of light they want to use in their experiment. This allows for high precision and time-dependent measurements that would be impossible under other circumstances.

In short, synchrotron light sources “reveal the structure, chemical composition, electronic properties, and other features of specimens critical to materials science,” among other disciplines, according to Chemical & Engineering News.

Bio and environmental sciences

The same mechanisms that permit a look inside materials also allow researchers to examine macromolecules, proteins, and other structures. Crystallography—the science of crystal structures and properties—is an important application of synchrotron radiation. But it’s in atmospheric research and clean combustion technologies where applications may be more visible to the public in the years to come. For example, a 2018 study on auto-oxygenation using synchrotron radiation from Berkeley’s Advanced Light Source provided insight into atmosphere pollution because the chemistry between that and fuel combustion inside an engine is similar. The findings enabled more accurate fuel combustion simulations, but could, ultimately, help improve simulations predicting air pollution and global temperature, according to Phys.org.

Synchrotron radiation discoveries and successes

This is just scratching the surface of light source uses. Entire books have been dedicated to the subject. So instead of diving further into the research applications and theory, we’ll look at a couple far-reaching discoveries that apply to the masses.

Giant magnetoresistance

One of the most far-reaching discoveries to come out of synchrotron radiation research is giant magnetoresistance. This type of quantum mechanical process is observed as a big change in electrical resistance depending on the alignment of ferromagnetic layers in a structure. The main application of this phenomena is in magnetic field sensors, like those used in hard drives and other computer parts. According to Ennen et al. in a 2016 paper, applications of this technology are “impressively broad, ranging from applications in the air- and space or automotive industry, non-destructive material testing, or the compass functionality in mobile phones to biomedical techniques, like biometric measurements of eyes and biosensors.” Put simply, the modern technological world as we know it would not be possible without the discovery of giant magnetoresistance.

Tamiflu

Another wide-reaching discovery is the anti-flu drug Tamiflu. The structure of one of its active ingredients was determined using synchrotron radiation. The drug is widely used today and was a go-to treatment for the 2005 H5N1 flu outbreak in Southeast Asia.

Synchrotron Nobel Prizes

There have been several Nobel Prizes awarded that depended on synchrotron radiation. One was the 2009 Nobel Prize in Chemistry given to Venkatraman Ramakrishnan, Thomas A. Steitz, and Ada E. Yonath for their work in figuring out the structure of the ribosome. This research used, in part, X-ray crystallography, a method made possible by synchrotron light. “Venkatraman Ramakrishnan and other researchers were able to collaborate to map the structure of ribosomes, made up of hundreds of thousands of atoms,” according to the Nobel Prize website. “Among other applications, this has been important in the production of antibiotics.” The Argonne National Laboratory synchrotron and the Stanford Synchrotron Radiation Lightsource helped win the 2012 Nobel Prize in Chemistry for “the structure and functioning of a protein complex on the surface of human cells, called a G-protein-coupled receptor, that receives signals from the cell’s environment and is a key target for drug development,” said Stanford National Accelerator Lab.

The future of synchrotron radiation: Free-electron lasers

First-generation synchrotrons were built in the mid-1900s and often couldn’t be iteratively upgraded. Second-generation machines, however, were constructed with the idea of continuous improvement. Many have been improved with successive add-ons over time, boosting their power and refining their capabilities. Such piecemeal improvement can only take us so far. The third generation of these accelerators and beyond will likely involve entirely new technology and new construction.

One of the possibilities for third-generation machines is the use of free-electron lasers (FELs) as the beam source itself. Regular lasers make light by jiggling electrons bound inside atoms. FELs make light by using magnets to agitate electrons that are unbound from atoms, a.k.a. “free” (hence the name). The FELs use the same undulators as those in storage ring-based light sources, but thanks to an electron clumping effect called “micro-bunching,” the resulting synchrotron radiation is orders of magnitude more coherent and intense. Another important feature is their ability to generate shorter—femtosecond, in this case—pulses with the same intensity in each peak that current synchrotron sources emit in one second. Such pulses can produce X-rays millions of times brighter than today’s most powerful light sources. This kind of speed, precision, and power would allow researchers to probe matter in new ways. While that might sound innocuous on its face, it is in fact remarkable because scientists will be able to scrutinize almost unimaginably small, complex structures. With next-generation synchrotron light sources, we have a microscope capable of peering into the very chemical and atomic processes that make up life and the world around us. See a synchrotron light source simulation with Sirepo.

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How Particle Accelerators Work: From Linac to Synchrotron

Accelerating particles is a simple concept: an electric field moves a charged particle from one location to another. Since electric fields don’t act on neutral particles (like neutrons), only electrons, protons, ions, and various antiparticles can be accelerated like this.

How much the particle speeds up depends on the strength of the electric field. Over the last century, accelerator design has become more sophisticated to achieve higher-energies, but basic principles remain constant. Where things get really fascinating, however, are the new applications for particle accelerators and beams.

To understand the full picture of accelerator science, we’ll explore not only how modern machines work, but also how they’re used in everyday life.

Contents

Why we accelerate particles

More than 30,000 accelerators are in use around the world. The most famous is the Large Hadron Collider (LHC) at CERN. While it’s the world’s largest and most powerful particle accelerator, it’s an exception.
Yes, they’re most well-known for helping scientists explore the foundational building blocks of the universe, but accelerators are also used for cancer therapy, food packaging, materials research, imaging broken bones, archeology, art, and more. They’ve even improved the taste of chocolate and helped to make baby diapers more absorbent.
Before diving into the mechanics and physics of accelerators, let’s explore some of these everyday applications in greater detail.

Particle accelerators applications

Cancer therapy

One of the most practical and impactful uses for particle accelerators is in cancer treatment. Conceived in the 1950s, proton therapy, where a tumor is bombarded with a beam of protons, remains one of the most cutting-edge treatment for cancerous tumors. These charged particles damage the DNA of cancer cells, killing them.
Early model of the linear accelerator developed to treat cancer.

There are advantages to treating with protons over traditional radiation therapies, which attack the tumor with X-rays. Radiation biologist Kathryn Held explained it best in a presentation at the 2014 AAAS meeting: “We could cure a very high percentage of tumors if we could give sufficiently high doses of radiation, but we can’t because of the damage to healthy tissue. That’s the advantage of particles. We can tailor the dose to the tumor and limit the amount of damage in the critical surrounding normal tissues.” Proton beams have a very handy property called the Bragg peak, which means the particles can precisely target tumors and deposit most of their cancer-killing energy in the tumor itself, rather than flowing out through the body and damaging healthy tissue.

Food packaging

Have you ever wondered how a refrigerated Thanksgiving turkey can be so perfectly plastic wrapped? The short answer is, accelerators.
It works like this: shrink wrap is often made of polyethylene plastic. Polymers, a.k.a. the molecules, are strung together like beads on a necklace. The plastic is comprised of many of these necklaces.
When a beam of particles (usually electrons) from an accelerator hits the polymer, it ionizes the material. Ionization allows these necklaces to form new molecular bonds with each other in a phenomenon called “crosslinking.”

This process makes the plastic much stronger because the molecular structure is now interconnected, like a net.

When crosslinked plastic is heated, it doesn’t melt. This is key because “[w]hen cooled to room temperature, the [crosslinked] plastic retains its expanded shape. Place something inside it, such as a Butterball turkey, and apply heat, and the plastic shrinks back down to its original size, resulting in an air-tight wrapping,” explains Elizabeth Clements in a Symmetry article.

Art and archeology

Priceless works of art pose a unique challenge in identifying their constituent materials, divining their provenance, and understanding how they’re made. Plus, their often delicate and irreplaceable nature requires a nondestructive and, if possible, nonsampling solution.

Enter, accelerators.

For decades, the Centre for Research and Restoration of the Museums of France has used ion beam analysis (IBA) to analyze works of cultural heritage. First introduced in 1957, IBA has become the go-to solution for historians to gain insight into works of art and archeological artifacts.

With their accelerator, AGLAE, the Centre has identified the materials used in drawings of Italian Renaissance artist Pisanello, the pigments on an Egyptian Book of the Dead, and much more.

How particles are accelerated

How can one machine do all of the above? It comes down to electricity and magnetism. While accelerators come in three main types (explained further down), they all require some basic parts to function.

• A source of charged particles
• Electric fields to accelerate those particles
• Magnetic fields to control the particles’ paths
• A vacuum chamber through which the particles travel
• Detectors for measuring particle attributes

Charged particle source

Sources of charged particles can be a gas or even a solid material, like metal. To get the particles themselves, the donor gas or metal is excited and particles are stripped off.

For example, the huge LHC uses a single bottle of hydrogen gas to provide its protons. It’s replaced only twice a year.

Electromagnetic fields

Charged particles are then shot through a “gun” into the accelerator itself, where electric fields accelerate them, increasing their energy.

The amount of energy a particle acquires—measured in electronvolts (eV)—as it moves through an electric field is determined by the difference in electric potential between where it enters and exits the field. Higher potential means higher particle energy.

Magnetic fields focus and steer the particle beam. If it’s a circular accelerator, they also bend the beam’s path into a complete circle.

To get an idea of what this looks like, the above GIF illustrates a linear setup with an alternating electric field accelerating red particles. The particle gun is represented by S, the electric field by E, and its charge by red and blue +/-.

 

To accelerate particles, both cyclic and linear accelerators typically use alternating electric fields generated by electromagnetic waves. These can range from radio- to microwaves. The field in adjacent accelerating cavities are out of phase with each other, so that the field ramps back up right as the particles transition from one cavity to the other.

 

This means the particle “feels” a constant acceleration every time it passes through a cavity. These individual “pushes” add up over time as the particles move through more fields, resulting in a big net “push,” accelerating them to high energies.

Vacuum chambers

All of this action happens inside vacuum chambers to avoid contact with the atmosphere. This is vital because charged particles are so small that they can be easily bumped off course or lose energy through collisions with the air.

Particle detectors

These accelerated particles can be smashed into targets or into each other (if there are two beams accelerating in opposite directions).

 

That’s where detectors come in. They can be as tailor-made as the interactions researchers want to observe. We won’t go into all the details here, but check out this short summary of how particle detectors work.

What are the different types of accelerators?

There are two main accelerator families: linear and circular. Within those, there are many designs. The three most common types of accelerators are linear accelerators, cyclotrons, and synchrotrons.

Linear accelerators

Linear accelerators (or linacs) are so named because of their shape. In a linac, particles are accelerated through a sequence of electric fields in a straight line, gaining energy the further they travel.

 

Like cars drag racing down a highway, they only go in one direction, accelerating all the while. The more fields they pass through, the more they accelerate, and the more fields, the longer the linac.

 

Before the advent of flatscreen TVs, many people had accelerators sitting in their living rooms. That’s because cathode ray tubes, the devices used to generate images on screen, are a kind of linac.

Today, the largest linac is the Stanford Linear Accelerator at SLAC National Accelerator Laboratory, which measures 2 mi (3.3 km) long. It can accelerate particles up to 50 gigaelectronvolts (GeV).

Circular accelerators

In the circular family of accelerators, there are two main types: cyclotrons and synchrotrons.

Cyclotrons

In a cyclotron, particle beams are steered through relatively weak electric fields many times, gaining energy while traveling outward in a spiral towards a target.

Invented around 1930, the first cyclotron was only 4.5 inches in diameter—small enough to hold in your hand. The largest ever built is 59 ft (18 m) in diameter. Called TRIUMF, it’s located in British Columbia, Canada.

 

In this kind of accelerator, charged particles are injected into a vacuum chamber between two hollow D-shaped metal electrodes, called dees, in the cyclotron’s center.

 

Electrodes provide an alternating radio-frequency voltage that switches between the two dees. Precise timing accelerates the particles and increases their path’s diameter, changing it into the spiral indicated in dashed lines above.

 

A large magnet provides a constant magnetic field which bends the particles’ path so they stay within the cyclotron and keep accelerating, gaining more energy in each revolution.

Synchrotrons

Synchrotrons are a type of circular accelerator that can reach very high energies. They do this by keeping the electric and magnetic fields synchronized with the particle beam as it gains energy. Hence, the name.

Unlike the spiral motion of a cyclotron, particles move around a circle inside a synchrotron. (Think NASCAR races on a circular track.) As the particles accelerate, the electromagnetic field in the ring increases to keep pace.

 

A synchrotron beam isn’t continuous. Instead, particles are clustered into “bunches.” Each bunch is shaped like a small, ultrathin noodle. The bunch could be a few centimeters long, but only a tenth of a millimeter wide.

 

These bunches contain something like 10¹² particles, a density that still falls far short of the number of atoms that would be in an actual noodle of that size.

The Next Frontier: Higher Luminosity and Smaller Machines

From CERN’s massive and complex LHC, which holds the record for largest machine ever built, to comparatively run-of-the-mill linacs in hospital X-ray rooms, we’ve become very good at building particle accelerators.

So, where do we go from here? Have we reached the limit on what we can build or what accelerators can do? The answer is a resounding no.

 

There are many roads for advancing accelerator physics. Two with far-reaching potential are increasing beam luminosity and making accelerators very, very tiny.

Why luminosity matters

One indicator of accelerator performance is luminosity. It provides a metric for how many interactions you can see and how much data you can produce, which means more potential for discoveries of new physics.

 

That potential is the focus of the High Luminosity LHC (HL-LHC) project. According to CERN, the project “will allow physicists to study [known] mechanisms in greater detail, such as the Higgs boson, and observe rare new phenomena that might reveal themselves.”

 

Scheduled to start operation in 2027, it aims to increase luminosity by a factor of 10 over the original LHC’s design value. Experts estimate the upgrade will produce 15 million Higgs bosons annually. That’s up from the three million the LHC made in 2017. Increasing this number is important for scientists at CERN, as detectors can only clearly observe a small fraction of the Higgs bosons that are produced.

 

Making many more bosons could lead to observations that expand on the Standard Model of particle physics, changing our understanding of the most basic building blocks of matter.

Miniaturizing Accelerators

Researchers are also making accelerators smaller than ever. One example is the accelerator-on-a-chip—a nanoscale particle accelerator made by Stanford University researchers. Presently in the proof-of-concept stage, it demonstrates that accelerators can be made cheaper and smaller than behemoths like the LHC.

“The largest accelerators are like powerful telescopes. There are only a few in the world and scientists must come to places like SLAC to use them,” electrical engineer and team lead on this project Jelena Vuckovic said in a Sci Tech Daily article. “We want to miniaturize accelerator technology in a way that makes it a more accessible research tool.”

 

Along with that accessibility, making accelerators more compact has manifold possibilities in other applications. Today, X-ray machines take up whole rooms, perhaps with technology like this they could be made portable. Perhaps cancer therapies could be made cheaper with easier-to-manufacture equipment.

 

One thing is certain, from the largest to the smallest, the future of accelerators is one of vast possibility for both fundamental science and industry application.

Want to see how particle accelerators work?

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Three Reasons Why You Should Wrap Legacy Codes in GUIs

Scientific research, no matter the subject, depends on specialized codes to model complex systems. Scientists are constantly developing tools for their own research that could benefit others, but these codes, scripts, simulations, and programs are rarely shared. Not because they aren’t useful, but because sharing them can be challenging.

Most often, scientists develop code that runs locally on the command line. Meaning, a user interacts with the computer via commands given in text form, rather than using menus or graphics.

Command-line interfaces (CLIs) can be difficult to learn for novices. There are no visual cues; one must recall what the system can do and the commands to make it happen. To get them up and running, confusing text input files are also needed.

One solution to making knowledge transfer easier, onboarding processes faster, and collaboration less cumbersome? Wrap your command line code in a graphical user interface (GUI). GUIs have the advantage of being easy to use and simple to learn, which opens a code up to a wider group of users who get up to speed faster.

In this post, we cover three ways GUIs improve productivity and business outcomes.

1.   Better succession planning

Frequently, mission-critical scientific codes have one expert—the code author. But what happens when that person moves on to another project, retires, or otherwise becomes unavailable?

Companies and labs can be left scrambling.

This is where good succession planning can make a big difference. If you have a simple, quick way to transfer legacy code resources and knowledge, everyone can get working faster. One way to do that is to wrap that important code in a GUI.

GUIs are simple to learn and don’t require advanced or specific coding knowledge. This means that learning and using legacy code with GUIs can happen much faster than traditional command-line interfaces.

2.   Shorter onboarding processes

Another complication of single-person authorship is an arduous onboarding process. Teaching a new employee how to use a legacy code can mean weeks or more of learning before they can work independently.

If a project is time-sensitive, that onboarding could run longer than the project itself. This also adds cost because two people are working (teacher and student) when one trained person would suffice.

For example, say a summer intern is assigned to work on a project requiring the use of a legacy code. Even if they are familiar with coding, it can take weeks to get them up to speed on a particular legacy code. That means one or more people teaching that intern the ropes, adding cost. By the time they can work confidently, the internship could be over.

GUIs flatten the learning curve when compared to command-line interfaces, reducing onboarding time from months to days.

This is largely thanks to their visual nature. You don’t need to memorize commands for GUIs. You don’t need to be fluent in coding language for GUIs. Graphical interfaces allow complex systems and/or processes to be reduced to simple-to-execute actions. (This feature is especially useful since legacy codes often lack proper documentation.)

3.   Ready-made plots

Command line codes do not automatically produce graphical plots or other visuals. This means that after the code is run, the user must take multiple additional steps to produce a plot, increasing overall task time.

GUIs can be programmed to automatically produce plots in the same program. Reducing the time spent running ancillary plotting programs, and improving overall efficiency.

GUIs open legacy codes up to a broader community

Simply wrapping a legacy code in a GUI can solve major problems impacting your business right now by making people productive faster. It makes getting consistent visualizations straightforward, which can aid marketing efforts and improve ease of use. It also future-proofs your company, ensuring legacy code resources aren’t lost with staff transitions.

Bottom line, if you want to better your business in any of the above ways, it’s time to start thinking about wrapping your legacy code in a GUI.

Check out how GUIs on codes work in Sirepo

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