The European Space Agency (ESA) has launched a new mission that will take a closer look at nearby bright stars that are already known to have exoplanets orbiting around them. Dubbed the Characterising Exoplanets Satellite (CHEOPS), the 1.5 m probe is the first dedicated ESA mission to study exoplanets. It was launched today from the European spaceport in Kourou, French Guiana, at 08.54 GMT.
From a Sun-synchronous polar orbit with an altitude of about 700 km, CHEOPS will measure the brightness of the stars, looking for tiny dips associated with a transit – when an exoplanet passes in front of its star, blocking some of the light that reaches Earth. Rather than search for new planets, CHEOPS will study about 500 of the 4000 or so known exoplanets during a 3.5-year period. These planets have already been discovered from previous planet-hunting satellites such as NASA’s Kepler and Transiting Exoplanet Survey Satellite missions as well ESA’s Corot probe.
With a mass of 280 kg, CHEOPS contains a single optical Ritchey–Chrétien telescope with an aperture of 30 cm. It will measure the radius of exoplanets that have a mass of that between Earth and Neptune to an accuracy of around 10%. The probe will also study the atmosphere of larger planets – those that are around the size of Jupiter. The first data is expected in early 2020.
CHEOPS was selected in 2012 from 26 proposals as an “S-class” mission, which have a cost cap of €50m. It was launched together with the Italian space agency’s Cosmo-SkyMed earth-observation satellite as well as three CubeSats. According to ESA CHEOPS project scientist Kate Isaak, around 20% of the observing run will be available to “guest observers”. “Scientists from around the world will be able to capitalise directly on the unique capabilities of CHEOPS,” she says.
The CERN particle-physics lab in Switzerland is famous for the Large Hadron Collider (LHC), but that is not the only game in town when it comes to looking for new physics beyond the Standard Model. For example, the lab has an “Antimatter Factory” that looks for new physics by trying to measure tiny differences in the properties of hydrogen and antihydrogen.
It is written by the “PBC BSM study group”, which is an international team of 33 physicists. They considered 18 different proposals that could be built at CERN to “exploit” the lab’s accelerator complex and scientific infrastructure to look for new physics.
They say that the search for new physics beyond the Standard Model is motivated by four unexplained phenomena that are readily observed in the universe. These are neutrino oscillations; the abundance of matter and dearth of antimatter; dark matter; and cosmological inflation and dark energy.
Electric dipole moments
One avenue that has long intrigued me is looking for new physics by making precision measurements. One of my favourites is the idea of trying to detect the electric dipole moments (EDMs) of particles such as the electron or proton. Standard-Model symmetry rules prevent these particles from having EDMs, so measuring even the tiniest value would provide a glimpse of new physics.
Other ideas that are scrutinized in the report focus on detecting axions and axion-like particles (ALPS). Axions are hypothetical particles that were first proposed to resolve an inconsistency in quantum chromodynamics – the theory of how quarks and gluons interact to form particles such as neutrons. ALPs have yet to be discovered but they are expected couple very weakly to matter – thus making them candidates for dark matter. As a result, discovering axions could open windows into several mysteries beyond the Standard Model.
For a wide-ranging discussion of new experiments that could soon be searching for ALPs, EDMs and more, have a good read of the report. My favourite experiment name is KLEVER, which looks at the decay of long-lived neutral kaons (ΚL). The first two letters represent ΚL, but I am not sure about the “EVER”.
Researchers in California have discovered that thin hairs are stronger than thick hairs and able to endure greater tension before they snap. Tests of hairs from eight different mammals showed that thinner hairs tend to shear off, whereas thick hairs break cleanly – a discovery that could aid the design of bio-inspired materials.
Human hair has a hierarchical structure. Within the outer layer, or cuticle, is an inner cortex consisting of many small keratin fibres – around 5 μm in diameter and 100 μm in length – linked by chemical bonds. Within each of these fibres are smaller threads, 0.2–0.4 μm in diameter, which in turn consist of 7.5 nm intermediate filaments.
The protein-based structure of human hair gives it its strength and makes it resistant to deformation. The keratinous fibres stretch easily, and can be extended by up to 40 percent before breaking. Previous research has found that human hair has a tensile strength of around 200–260 MPa, which is comparable to steel. You could carry a person with 500–1000 human hairs.
Hair comparison
Curious to see how hair from other mammals might fare, material scientists and engineers at the University of California, Berkeley and the University of California, San Diego, US analysed hairs from humans, bears, boars, horses, capybaras, javelinas, giraffes and elephants. The diameter of these hairs varied from around 60 μm in humans to more than 350 μm in elephants and giraffes. Although the hairs’ basic morphology is comparable, the researchers found that their exact structure and diameter differ in ways that relate to their functionality.
The hair of capybara and javelina diverge from the other samples in several respects. The javelina, a pig-like animal native to Central and South America, raises the hairs on its back for defence. The cortex of its hair had a closed-cell foam-like structure, rather than the fibrillar structure found in other hairs. This increased its stiffness, making it similar to a porcupine quill, the team report.
The hair of the semi-aquatic capybara, in contrast, has a “twin” structure. This gives it an oval-like cross section with a central groove that lets water run off, helping the animal dry faster.
Scanning-electron microscope images of capybara hair. a) The cuticle arrangement and “twins” appearance. b) A shear fracture of one twin hair. c) Fibres close to the boundary, which appear brittle and stiff. d) Fibres pulled out from the fracture surface of the twin hair. Reprinted from Matter2 Wen Yang, Yang Yu, Robert O Ritchie, Marc A Meyers, “On the Strength of Hair across Species”, pp1-14. Copyright 2019, used with permission from Elsevier.
The researchers pulled individual strands of hair apart until they broke. They found a clear correlation with tensile strength decreasing with increasing hair diameter. This also applied to hairs from the same species. For example, thin hair from a child was stronger than thicker hair from an adult.
When they studied the broken hairs with a scanning electron microscope, they found that hairs greater than 200 μm in diameter, such as those of boars, giraffes and elephants, tended to fracture, with a clean break. Thinner hairs, however, such as those of humans, horses and bears, sheared.
“Shearing is when small zig-zag cracks are formed within the material as a result of stress,” explains Wen Yang, an engineer at the University of California, San Diego. “These cracks then propagate, and for some biological materials, the sample isn’t completely broken until the small cracks meet. If a material shears, it means it can withstand greater tension and thus is tougher than a material that experiences a normal fracture.”
Yang says the findings, which were published in the journal Matter, could inspire the design of synthetic materials. “If we can create metals that have a hierarchical structure like that of hair, we could produce very strong materials, which could be used as rescue ropes and for constructions,” she explains.
A team from Cornell University has discovered that seemingly unimportant parts of the micro-structure of bone are actually critical to their ability to withstand long-term wear and tear (PNAS 10.1073/pnas.1905814116). This finding could lead not only to advances in studies of osteoporosis, but also to improvements in ultralightweight material design.
Doctors often use X-ray imaging to determine the density of bone and find weak spots before diagnosing osteoporosis. However, X-ray imaging only provides information about load-bearing capability and doesn’t give any information about the lifespan of the bone.
The research team, led by senior author Christopher Hernandez, was interested in bone fatigue and investigating how bone wears down over time because fatigue, the result of repeated load-bearing, has been neglected in previous studies of bone structure.
Bones have a complex internal structure formed by interconnected vertical plates and horizontal rod-like struts. When scientists talk about bone strength, they are referring to the strength of the vertical plates parallel to the direction of force. These bear the most weight, while the horizontal rods have previously been thought to be unimportant in load bearing. In this research, however, the team showed that it is in fact these horizontal rods that define the lifetime of the bone and its ability to resist fatigue.
Bone-breaking work
After testing bones from donors under repeated weight loading, the researchers found that the amount of damage to the bone was not linked to bone density or other measures of microstructure. In an unexpected result, they found that it was actually the thickness of the horizontal rods in the bone, previously thought to be unimportant to weight-bearing, that was linked to the amount of damage caused.
“If you load the bone just once, it’s all about how dense it is, and density is mostly determined by the plate-like struts,” Hernandez describes. “But if you think about how many cycles of low-magnitude load something can take, these little sideways twiggy struts are what really matter.” The researchers theorized that these horizontal rods act as sacrificial elements of bone structure: taking damage to protect the load-bearing vertical rods. As people age, the horizontal rods are lost, increasing the probability that the bone will break.
Using a 3D-printer, the researchers designed and manufactured structures with a similar micro-architecture to bone structure. By varying the thickness of the horizontal rods, they were able to increase the material’s lifetime by up to 100 times, showing that the effect is not specific to bone and can be generalized to other materials.
Material improvements
This discovery is important beyond studies of osteoporosis. Many modern materials also have a micro-architecture that allows them to be extremely strong as well as lightweight. If these materials are to be used in more durable devices such as vehicles, they will need to be able to withstand fatigue.
A typical strategy to improve efficiency when designing micro-architectured materials is to remove some of the struts perpendicular to the weight-bearing direction, as they don’t experience high loads. However, the research team has shown that this strategy reduces a material’s lifespan. This discovery could lead to more durable lightweight materials for a variety of applications, including the aerospace industry.
“If you want to make a durable device or a vehicle that is lightweight and will last a long time, then it really matters how many cycles of loading the part can take before it breaks” Hernandez explains. “The mathematical relationship we’ve derived in this study lets somebody who’s designing one of these lattice structures balance the needs for stiffness and strength under a single load with the needs for tolerating many, many lower-level load cycles.”
Wide appeal: Better ways of bringing science to the public, such as here in Nairobi, can boost the subject. (Courtesy: Mawazo Institute)
All too often, science is carried out by people from the same demographics – namely, white men in the global north. The diversity problem in science is well recognized and many institutions have begun to tackle it through a range of initiatives. Despite those efforts, however, the issues persist and the representation of women and other minorities lags behind men in most science, technology, engineering and mathematics (STEM) disciplines.
There also remains a failure to tap into the scientific potential of entire regions such as sub-Saharan Africa, which accounts for 15% of the global population but less than 1% of published research in STEM subjects. This problem is influenced by a range of factors, such as biases shared by both men and women as well as structural barriers in academia. It is also affected by socio-economic development in the global south and “leaky” pipeline issues. The work and ideas of scientists in Africa often have very limited visibility and impact in public life. Yet local perspectives on complex issues are crucial to help people navigate technological challenges and opportunities.
We believe that inclusive and diverse public engagement can be an important – but often overlooked – tool to help create a more representative and vibrant global scientific community. In Ireland, for example, the past decade has seen an explosion of events and support for public engagement with science. Arts-based approaches are especially strong in Ireland, a phenomenon that can be attributed both to the strong literary and theatrical tradition in the country, as well as the influence of those that have pioneered co-equal science and arts spaces such as the Science Gallery.
Bright Club – a variety night combining academic research with stand-up comedy – began in the UK in 2009. The model – in which academics develop stand-up-comedy sets about their work – transferred to Ireland in 2015, where to date more than 70 events have run. Crucially, Bright Club includes training for academics based on improvisation and theatre to teach them the principles of comedy and performance.
Since each event includes not only scientists but also researchers from social science and humanities alongside comedians and other performers, the audience is broader than at typical science outreach events. The training element also empowers researchers from underrepresented groups who might not feel confident to volunteer for a public-facing event without support. The diversity in discipline, speakers and location all draw in diverse audiences, breaking down barriers so that more people can access scientific knowledge.
Diverse and collaborative
The experience of successfully exporting the Bright Club format to Ireland is one that can certainly be replicated elsewhere. Kenya, for example, needs a community of skilled science ambassadors to better integrate science into the wider culture. Borrowing from Bright Club’s model, the Mawazo Institute, based in the Kenyan capital, launched the Nairobi Ideas programme. This includes platforms such as free public events, podcasting and blogging for local scientists and members of the public to share perspectives on the role of science and innovation in our daily lives. The institute also trains local scientists – especially women – in public engagement and science communication, shaping them into public-facing researchers.
There are some words of caution with this model – adapting public engagement across borders is an exercise in cultural sensitivity. Even in the same language, use of slang and metaphors can be quite different in different regions, even between regions within the same country. The level of formality expected from researchers can vary widely and communication styles – such as directness of speech and use of emotion – can be quite different.
This can be a disadvantage or an advantage when developing public engagement across borders. As two immigrants ourselves, we found great strength in sharing these tools with researchers, building capacity for new types of public engagement that can be carried out by a broader range of researchers. Indeed, our experiences corroborate studies showing that participation in public-engagement activities can enhance scientific identity and support people to remain in science, which is particularly important for those from underrepresented backgrounds.
Public engagement not only makes science more accessible, but also makes the scientific community more vibrant, diverse, and collaborative. We need more cross-cultural opportunities for science engagement where partners are equal and audience reach is beyond typical demographics. Bringing science to the public leads to better and more diverse science for a more equitable world.
Nanostructures composed of DNA building blocks can be made to self-assemble and disassemble in response to certain environmental conditions. The new technique has been developed by Francesco Ricci and colleagues at the University of Rome, who engineered the process by attaching specific antigens to the molecules, which could then only bind to specific connecting antibodies. Their research could bring about a variety of new applications in nanomedicine.
DNA molecules are ideal building blocks for nanoscale devices because they are inexpensive and easy to make and have highly-predictable base-pairing mechanisms. By simply binding the molecules together, researchers can construct intricate, origami-like structures that can be microns in size.
Structures that have been built already include the practical – such as cages that can be opened and closed – and the fanciful, including a microscopic copy of the Mona Lisa. A desirable next step for this idea is to create nanostructures that assemble and disassemble themselves in response to certain environmental cues – something that could be particularly useful for medical applications.
Y-shaped proteins
Ricci’s team achieved this using IgG antibodies, which are Y-shaped proteins. As essential components of the immune system, these molecules typically operate by binding to and then immobilizing pathogens. The antibodies respond to certain environmental triggers, including temperature and pH. Thousands of types of IgC antibodies are known to exist, with the tip of each individual Y-prong binding to highly specific groups of molecules associated with particular pathogens, known as antigens. In medical applications, they are critically important as natural biomarkers of diseases.
In their study, Ricci and colleagues achieved synthetic DNA self-assembly for the first time by first attaching specific antigens to the molecules. When the relevant antibodies were released into the solution, each individual Y-prong attached itself to an individual antigen, linking molecules together. This then enabled the blocks to quickly assemble themselves into hollow tubular structures that were up to a few microns in length. Finally, they disassembled themselves when the researchers released a second specific antibody into the solution, which disabled the IgG-antigen bounds.
Since antibodies are produced naturally to target foreign molecules, Ricci’s team believe that IgG antibodies are the ideal agents for building intricate and intelligent nanostructures in highly specific parts of the body. They predict that their technique could have diverse clinical applications, especially for drug delivery and diagnostics. Through further studies, they describe how improvements in the technology could bring about cell-free synthetic biology systems, capable of performing logical functions that mimic those of electronic circuits.
NV diamond sensor. Courtesy: Ella Marushchenko for Norman Yao’s group
Quantum sensors based on nitrogen vacancy (NV) colour centres in diamond can be used to probe the magnetic and structural properties of materials at extreme pressures. This is the finding of three independent research teams reporting their work in Science last week.
In the past, high-pressure experiments have provided important insights into how materials behave under the crushing forces in the Earth’s mantle, improving our comprehension of earthquakes. Scientists have also used high-pressure techniques to explore pressure-induced magnetism and investigate new materials with superior physical properties such as extreme hardness. Recently, researchers even discovered near-room temperature superconductivity in hydride materials that are compressed to more than 106 atmospheres.
The anvil cell
The main way to study materials under such great pressures is to use millimetre-sized anvil cells made from diamond or minerals such as moissanite. These work by squeezing a sample between the flattened tips of two pieces of very hard material. The small size of the tips makes it possible to reach pressures of more than 400 GPa or 4 x 106 atmospheres with only small applied forces.
The main problem with such measurements is that the samples – which are typically tiny, at just tens of microns across – need to be contained in a bulky pressure vessel. This set-up drastically limits the type of measurements that can be performed. Sensitive measurements of magnetization, for example, are difficult because the magnetism of the anvil cell is thousands of times greater than that of the sample itself.
NV colour centres as probes
The three research teams have now overcome this problem by using a defect in diamond, known as the NV colour centre, as a magnetic-field probe. These centres, which act like tiny quantum magnets with different spins, occur when two neighbouring carbon atoms in diamond are replaced by a nitrogen atom and an empty lattice site. When excited with laser pulses, the fluorescent signal emitted by the centres can be used to monitor weak local magnetic changes in a nearby sample. This is because the intensity of the emitted NV centre signal changes with the local magnetic field.
Diamond becomes a powerful scientific tool. The image shows a diamond anvil used to create high pressures as well as to sense magnetic field distributions in a superconductor. Courtesy: Siu Fai Hung
One of the three teams, led by Sen Yang and Swee K Goh of the Chinese University of Hong Kong, dispersed diamond particles containing NVs onto their sample (an iron-pnictide superconductor with the chemical formula BaFe2(As0.59P0.41)2) before placing it in a moissanite anvil cell. Thanks to the material’s spin-dependent fluorescence rate, and the fact that it is transparent, the researchers were able to measure the electron spin resonance (ESR) spectra of the NV centre optically. They then used this spectral measurement to determine the magnetic field of the sample with a sensitivity approaching microtesla.
The Hong Kong team also determined the superconducting transition temperature (Tc) of their sample. At temperatures above the Tc, the magnetic field felt by the NV centre is the same as the applied magnetic field. When a sample of superconducting material is cooled below Tc, however, it begins to repel an applied magnetic field – a phenomenon known as the Meissner effect. This superconductivity-induced expulsion of the magnetic field from the sample alters the field profile near the surface of the material, creating effects that are “felt” by the NV centres on the sample surface. The researchers derive the Tc through careful analysis of the field distribution, using the NV centres to sense both the magnitude and direction of the magnetic field at high spatial resolution.
Yao and colleagues prepared a thin (50 nm) layer of the defects a few nanometres below the surface of the pressure chamber on which their sample of iron and gadolinium is positioned. The researchers then shone a green laser on the defects. By measuring the resulting fluorescence, they monitored weak local magnetic changes in the sample in the same way as Yang and Goh’s team did. Next, they reconstructed an image of the NV response to produce a spatially-resolved map of the magnetic field emanating from the sample. They use this information to determine the sample’s magnetic dipole moment. When they repeat the experiment at different pressures and temperatures, they find that the dipole moment changes abruptly, which corresponds to a magnetic phase transition in the sample.
New kind of sensing protocol
The lead author of the Berkeley group’s study, Satcher Hsieh, says that their technique is new because instead of measuring a static magnetic signature, it relies on measuring magnetic “noise” emanating from the sample. Such noise arises because electrons in a metal are free to move around, and their motion generates a fluctuating magnetic field that the sensor can identify. Depending on whether the magnetic phase is ordered or disordered, the electrons may scatter off the spins with different amplitudes, and this changes the amplitude of the fluctuating field. “In our work, we measure a common magnetic transition (paramagnetic to ferromagnetic), but in the long term we hope to use this technique to identify more exotic magnetic phases,” Hsieh says.
The Berkeley team’s approach is also the first to measure all six components of the stress tensor at high pressures. As such, Hsieh says it may help further our understanding of high-pressure phase transitions that are driven by shear stresses, as is often the case for minerals found deep inside planets.
In-situ quantum sensors
Meanwhile, Roch and colleagues at ENS Paris-Saclay used a similar technique to image how the magnetization of an iron bead evolves as pressures of up to 30 GPa are applied. In their work, they imaged the magnetic field profile of an iron pellet undergoing a magnetic phase transition between the (ferromagnetic) alpha crystal structure and the (non-ferromagnetic) epsilon crystal structure, which occurs at around 15 GPa. They also imaged a magnesium boride (MgB2) sample as it crossed its superconducting transition state (at 7 GPa) by detecting the Meissner effect.
ENS team members Margarita Lesik and Thomas Plisson adapting a transportable NV microscope. Courtesy: JF Roche
Roch explains that integrating NV centres into the diamond anvil itself means that his group’s quantum sensors are in direct contact with the sample being tested. This approach allows the researchers to probe the materials’ magnetic properties as well as strain despite the minute size of the sample. It will also enable them to measure phenomena such as pressure-induced high-spin low-spin magnetic ordering and the superconductivity of novel superconductors (like the hydride materials H3S and LaH10) with unprecedented accuracy and resolution, he says.
Strongly correlated electron systems
Members of the Hong Kong team say they are now using their technique to study various strongly-correlated electron systems under high pressure. For instance, they are investigating how superconducting systems behave while simultaneously using pressure to tune the strength of electron-electron correlations.
The Berkeley and ENS Paris-Saclay teams, for their part, say they would like to study materials like the high-pressure hydrides, which become superconducting at just 10 degrees below room temperature. “Our group is now also measuring phase transitions of the magnetic minerals present in Mars’ crust to better understand Martian magnetism,” Hsieh says. The group is also studying the magnetic properties of a new iron-bismuth compound that was recently synthesized under high pressure.
Towards higher pressures and larger sample sizes
Roch and his colleagues point out that it would be interesting to investigate ways of detecting the onset of superconductivity by optical means at even higher pressures. Extending their work to pressures of greater than 100 GPa would be a challenge, since the spin readout contrast of the NV centres dramatically reduces at pressures above 60 GPa. They suggest that this problem might be solved by engineering NVs via controlled nitrogen doping during the (plasma-assisted) growth of the diamond layer or by laser writing the NVs. These fabrication processes can bury a thin sheet of NV centres at a depth at which strain in the anvil might be less damaging.
Yao’s group also is pursuing higher-pressure studies, but with a somewhat different approach. “We are trying to excite the NV centres using a different colour excitation laser, which we think may provide sufficient energy to extend their use to 100 GPa and beyond,” explains Hseih.
The three groups agree that their different techniques are complementary, offering powerful new ways of probing matter at extreme pressures. Such techniques could be extended to atomic diamond defects other than NV centres, such silicon-vacancy centres, or indeed defects in materials other than diamond. Some examples include the optically active defects present in moissanite (6H silicon carbide), which can be manufactured at centimetre or larger scales — unlike diamond anvils, which are just millimetres across. Such defects could thus be used to study larger sample sizes.
According to Roch, the NV probes might also be coupled to X-ray beamlines, such as those in synchrotron facilities, in the future. This would make it possible to image samples at even smaller spatial resolutions – far below 100 nm for 4th-generation synchrotrons, for example. The X-ray diffraction patterns obtained could unambiguously identify the material being probed in the anvil cell. Combining the high spatial resolution with the magnetic images from the NV “magnetic microscopes” is likely to lead to new discoveries in the properties of high-pressure materials, he says.
“All three sets of results clearly demonstrate that this is only the beginning for NV probes and high-pressure physics studies,” he tells Physics World. “It is a very exciting time.”
The recent meeting, Physics-based Contributions to New Medical Techniques, examined how physics technologies are employed to help develop a diverse range of medical applications. One area in particular in which physics has played a vital role is the evolution of particle therapy systems and techniques.
Hywel Owen from the University of Manchester gave meeting attendees an introduction to the UK’s two NHS-funded proton therapy centres, at The Christie in Manchester and UCLH in London. He noted that a number of university academics around the UK are collaborating with these centres to improve the science and technology of radiotherapy. The Christie, which began proton treatments at the end of last year, has also constructed a research beamline at its proton centre, at which researchers from Christie Hospital and the University of Manchester will conduct novel research.
Although the UK centres offer state-of-the-art treatments, Owen explained that there are a number of opportunities to further improve the quality of treatments. Areas in which UK researchers are working include reducing treatment times, improving the imaging and accuracy of treatment, and developing use of alternative particles such as carbon ions and electrons.
Owen described his group’s work to develop the world’s first superconducting cyclotron that operates at 70 MeV. This system aims to provide a route to higher dose rate delivery for shallow treatments such as ocular therapy and will potentially give a better dose distribution than current technologies. The Cockcroft Institute has collaborated with Antaya – one of the world’s leading cyclotron developers – to produce a prototype; the larger magnetic fields obtained with superconducting magnets allow cyclotrons to be made much smaller and cheaper.
Another novel research development is the ProBE (proton boosting extension for imaging and therapy) linac – a joint project between the Cockcroft Institute, The Christie and CERN. ProBE is designed to accelerate protons from a medical cyclotron to the higher energies required for proton imaging. Owen explained that a prototype cavity has been manufactured and is predicted to achieve a gradient of about 54 MV/m. By adding it to a proton therapy centre’s beam transport system, whole-body proton imaging of adults becomes possible.
Rapid QA frees up treatment time
The big advantage of proton therapy arises from the fact that protons deposit most of their energy at a specific depth – the Bragg peak – and then stop, sparing surrounding normal tissue. But as Simon Jolly from University College London (UCL) explained, this highly localized dose deposition is also a disadvantage, as any range uncertainties necessitate the use of margins around the target volume. Effective quality assurance (QA) of proton therapy set-ups is thus essential to exploit the full dosimetric benefit of proton therapy. Unfortunately, such procedures can be time consuming.
Jolly described a prototype range measurement device under development at UCL that should enable faster and more accurate proton range measurements, thereby speeding up the daily QA process. “We are transferring technology from pure high-energy physics research to proton therapy,” he told the audience.
The prototype proton range measurement system. (Courtesy: Simon Jolly)
Multilayer ionization chambers (MLICs) can perform beam range measurements in just a few minutes, but can be bulky and expensive. The UCL device is similar to an MLIC design, but replaces the stack of ionization chambers with individual sheets of plastic scintillator, of the type used in the SuperNEMO double-β decay experiment. Jolly notes that this lightweight plastic is near-water-equivalent, provides high light output and has excellent energy resolution. Unlike MLICs, it is also capable of making measurements at FLASH dose rates.
To measure range, the proton beam is fired horizontally into the end of the stack of scintillator sheets. The device reads out the light signal from each individual sheet using a pixelated sensor placed on top of the stack (over the sheet edges). Beam range can then be estimated from the measured light dose distribution. The system is calibrated by shooting a high-energy proton beam through the entire stack in both directions.
Jolly and colleagues tested the prototype device at several sites, including MedAustron, the Heidelberg Ion Beam Therapy Center and the Birmingham Cyclotron, where it performed its first Bragg peak measurement last March. The system demonstrated a proton range reconstruction accuracy of about 100 µm, well below the clinical requirement of 1 mm.
The team also verified the radiation hardness of the prototype system by performing a “fry up”, at the Clatterbridge Cancer Centre. After continuous irradiation for an entire day, the device showed less than 5% reduction in peak light output and no change in range accuracy. “The detector survived almost 6500 Gy, about a year’s worth of dose,” Jolly noted. “The next step is to build a system for the clinic that is self-contained, easy to use and robust.”
I remember seeing the launch of the first Space Shuttle on TV while growing up in Mumbai, India, and from then on I was intrigued to learn more about space. To nurture this interest, my mother used to take me to see shows at the planetarium in Mumbai, and when Halley’s comet was close to the Earth in the late-1980s, we would wake up early in the morning to view it. Later, when I was doing my bachelor’s degree in physics at St Xavier’s College in Mumbai, I used to join its Natural Science Association’s annual trips to view the Perseid meteor showers from a remote location away from city lights. A college professor introduced me to two well-known astronomers at the Tata Institute of Fundamental Research in Mumbai. They kindly guided me through two separate literature surveys: one on the solar neutrino problem and another on life on other planets in our solar system. Surprisingly, some facts on the latter topic are making news in the media in the last couple of years.
I then was lucky to get a scholarship to study astrophysics at the University of Cambridge in the UK. I spent my first summer holidays at the Royal Greenwich Observatory helping astronomers with data analyses. Although I enjoyed working there, I realized that I did not wish to pursue this work in my career as I did not enjoy working on my own. The MSc course in physics of semiconductor materials science at the University of Bristol introduced me to transmission and scanning electron microscopy techniques, which I used for both my MSc and PhD theses. This expertise was also useful while I was a materials scientist at Alcan Laboratories in Banbury and for a short time at Innoval Technology, also in Banbury.
Did you ever consider a permanent academic career in materials science?
I used to get very frustrated when my academic supervisors and research associates constantly corrected the grammar in my theses and academic publications. This meant that later, I hated writing articles for publication. This put me off being an academic even though I still enjoyed teaching.
What made you want to do an MBA and what career path did you follow after?
I have always enjoyed learning new skills in my spare time and had completed evening classes in Banbury on car maintenance for women and flower arranging. While browsing the Open University catalogue in the late-1990s, I found a course that was very similar to an MBA. As I was self-funding my studies initially, a colleague encouraged me to undertake a distance-learning MBA at a more prestigious place, the Warwick Business School, as the costs were not too dissimilar. I thoroughly enjoyed what I was learning and also started applying some of the knowledge at work. I soon decided to step out of R&D to find a job in the “real world”, which also enabled me to earn more money. I know that money is not important in life, but it does help to have choices.
Although I had a lot of transferable skills, it was very hard to find an opportunity for a career change. I was exceedingly lucky that one hiring manager identified my skills and gave me a role as a business analyst in what was then called Holset Engineering, now known as Cummins Turbo Technologies in Huddersfield, West Yorkshire. I could do all the assigned tasks with great ease as they comprised data analyses.
After a few years at the company, I had the opportunity to become a Six Sigma Black Belt (an internationally recognized qualification in continuous improvement, designed for people whose job involves training or implementing process change). I then joined the purchasing department and become part of their “functional excellence” team. This role enabled me to build on my passion for business-process improvements and training. It also tapped into my materials science background as I developed a material compliance process. I had trained people in industry and academia while I was a materials scientist, and had also developed online aluminium metallurgy courses as part of a European aluMATTER project.
For the past 15 months, I have been responsible for global training of purchasing staff at Cummins. As part of my role I develop online courses for self-study too.
What were some of the challenges in moving from academia to industry?
To be honest I would not say it was a challenge at all. The only difference I observed initially was how punctual meetings were in an industrial environment, compared with a research organization. I still have the same freedom to plan my work as I did in research.
Having been in employment for almost 25 years, working life has changed considerably during this period. I do enjoy the ability to work flexibly these days, especially as I have stakeholders around the world and often have to work in the evening.
I am currently responsible for providing training options for all purchasing staff in Cummins globally. The company encourages staff to spend at least 5% of their time on training. Also, like many industries, we are continuously experiencing change and often it feels like trying to hop on a moving bus while riding a bicycle. As new processes and tools are brought into the department or as people change roles, they require training.
I believe in creating training options that people can tap into whenever they need and have the time for it, rather than making it mandatory. I offer blended training options: instructor-led classroom training, which at times is also broadcast using teleconference tools to make it a virtual offering, as well as online self-study courses and “office open hours” for some topics when people need ad hoc assistance.
While I am helping my colleagues to learn new things, I am also constantly learning about new purchasing processes and tools, learning methodologies and useful skills, such as the art of negotiation. I thoroughly love what I do, and often lose track of time, especially when I am working from home where there are no distractions around me.
How has your physics background been helpful in your work, if at all?
My scientific training has taught me to question to gain clarity, and to have attention to detail. Physics training generally goes hand-in-hand with some level of maths and statistics, which I have used at so many stages in my career. My materials science knowledge has helped me understand the need for material compliance in products and allowed me to develop a process that is now widely used in Cummins.
Do you have any advice for today’s students?
I would encourage today’s students to follow their passion and not follow the herd. If you enjoy what you do, success will automatically follow. Whenever you can, try and focus on emerging technologies and get your teeth into learning more about them. Remember that you will spend a large proportion of your waking hours at work, so it is extremely important that you enjoy whatever you are doing. Careers take time to develop, and you need to be patient and proactive.
Whenever possible volunteer for difficult tasks at work – the ones others are scared to undertake for fear of failure. Get summer placements and check out different career options in a safe environment. If you are lucky, your employer may sponsor part of your tuition fees or offer you full-time employment after you graduate.
Above is a four-hour video created by the American Chemical Society that provides a relaxing backdrop for a Christmas party. But, alas, there is also an educational aspect to the video. It includes the chemical structures of a vast number of compounds that make up Christmas themed objects such as gingerbread, candy canes and a Christmas tree – to name just three. The chemicals appear on the screen and then the Christmas object is named, so it’s a bit of fun to guess what’s next.
Are you looking for books about science for young people on your Christmas list? Physics World contributor Louisa Cockbill is compiling a “stereotype challenging booklist” for young readers. “We’ve already put the list to good use — selecting books from it for STEM Ambassadors to read at 11 events across Bristol during the city’s Storytale Festival in October,” says Cockbill.
At the moment the list is a simple spreadsheet, but it already contains more than 90 titles from authors including Lucy Hawking and Stephen Hawking. Cockbill and colleagues are keen to receive more suggestions, so please let them know about your favourites.
Ending on a second video, above is a performance of an updated version of Tom Lehrer’s “The elements” by Helen Arney, the Waterbeach Brass Band and folks from around the world. The video was put together by Chemistry World to celebrate 2019 as the International Year of the Periodic Table. See if you can spot the Physics World team belting out “bohrium” and then later on in the credits.
