Physicists Just Invented a New Particle Accelerator!

Quick Overview

Physicists have proposed a new "micronozzle acceleration" (MNA) method using ultra-intense lasers to accelerate protons over millimeters, achieving energies of nearly 1 GeV in computer simulations, a significant reduction in acceleration distance compared to traditional large hadron colliders like the LHC, which require hundreds of meters for similar energy gains.

Key Points: A new "micronozzle acceleration" (MNA) method has been proposed to accelerate protons using ultra-intense lasers. This method achieves proton acceleration over distances of mere millimeters, unlike traditional magnet-based accelerators that require hundreds of meters. Computer simulations show MNA can accelerate protons to nearly 1 Giga-electron-volt (GeV) energy. While promising for its compact size, MNA requires multi-petawatt lasers, which are large (10-20 meters) and expensive. The "excellent beam quality" claimed for MNA is relative to previous laser-based proton acceleration attempts, not comparable to the superior focus (<1°) and energy spread (<1%) of Wakefield accelerated electron beams. Current proton accelerators, used for applications like cancer treatment, are prohibitively large and costly for widespread use. The ultimate goal for particle accelerators is to reach energies exceeding 100,000,000 TeV to test fundamental laws of nature.

Context: Particle accelerators, like CERN's Large Hadron Collider (LHC), are crucial for probing fundamental physics by accelerating particles to high energies and colliding them. However, these machines are enormous, with proposed future colliders like the FCC reaching 90 km in circumference and costing tens of billions of dollars, making them economically unsustainable for broader applications. This has driven research into more compact acceleration methods, such as Wakefield acceleration for electrons, and now, the newly proposed micronozzle acceleration for protons.

Detailed Analysis

Physicists have introduced a novel "micronozzle acceleration" (MNA) scheme that utilizes ultra-intense lasers to accelerate protons over extremely short distances, specifically millimeters, in contrast to the hundreds of meters required by conventional magnet-based particle accelerators like the LHC. This new method, detailed in a "Scientific Reports" paper by Murakami et al., involves placing a micron-sized hydrogen rod inside a hollow metallic micronozzle within a vacuum chamber. An intense laser pulse, with a power of several petawatts, is then directed at the nozzle. This laser strips electrons from the nozzle material, creating a cloud of moving electrons. These electrons subsequently hit the hydrogen rod, ejecting protons. Crucially, the curved design of the nozzle's outgoing side becomes positively charged due to electron stripping, creating an electric field that both focuses and accelerates the protons. While this method has only been demonstrated through computer simulations, these simulations indicate that protons can achieve energies of nearly 1 Giga-electron-volt (GeV). This energy level is comparable to the LHC's pre-accelerator (PS), which is approximately 100 meters in diameter, highlighting the potential for significant size reduction. However, the multi-petawatt lasers required for MNA are themselves large (typically 10-20 meters long) and expensive. Furthermore, despite initial claims of "excellent beam quality," the simulated proton beams exhibit a wide focus angle of about 16 degrees and an energy spread of roughly 50%, which is considerably less precise than the sub-1-degree focus and sub-1% energy spread achieved by Wakefield accelerated electron beams. The "excellent" claim is relative to prior, less successful laser-based proton acceleration attempts. The development of more compact and cost-effective proton accelerators is vital for various applications beyond fundamental physics research, such as targeted cancer treatment, where current large-scale facilities limit widespread accessibility. The ultimate goal for particle physics remains to develop accelerators capable of reaching energies far exceeding the LHC's collision energy (e.g., 100,000,000 TeV) to explore new physics and test fundamental laws of nature.