Subject: Basic Sciences

Researchers from Collider Detector at Fermilab (CDF) Collaboration, in the US, announced that they have made a precise measurement of the mass of the so-called W boson.

Do you know?

There are four fundamental forces at work in the universe: the strong force, the weak force, the electromagnetic force, and the gravitational force. They work over different ranges and have different strengths. Gravity is the weakest but it has an infinite range.

What is W Boson?

• Discovered in 1983, the W boson is a fundamental particle.
• Together with the Z boson, it is responsible for the weak force, one of four fundamental forces that govern the behaviour of matter in our universe.
• Particles of matter interact by exchanging these bosons, but only over short distances.
• The W boson, which is electrically charged, changes the very make up of particles.
• It switches protons into neutrons, and vice versa, through the weak force, triggering nuclear fusion and letting stars burn.
• This burning also creates heavier elements and, when a star dies, those elements are tossed into space as the building blocks for planets and even people.

Debate over W Boson’s mass

• The weak force was combined with the electromagnetic force in theories of a unified electroweak force in the 1960s, in an effort to make the basic physics mathematically consistent.
• But the theory called for the force-carrying particles to be massless, even though scientists knew the theoretical W boson had to be heavy to account for its short range.
• Theorists accounted for the mass of the W by introducing another unseen mechanism. This became known as the Higgs mechanism, which calls for the existence of a Higgs boson.

What is the news?

• CDF researchers stated that this precisely determined value did not match with what was expected from estimates using the standard model of particle physics.
• This result is highly significant because this implies the incompleteness of the standard model description.
• This is a major claim, since the standard model has been extraordinarily successful in the past decades.
• Hence, physicists are looking for corroboration from other, independent, future experiments.

What is the standard model of elementary particle physics?

• The Standard Model of particle physics is the theory describing three of the four known fundamental forces (the electromagnetic, weak, and strong interactions while omitting gravity) in the universe and classifying all known elementary particles.
• It is a theoretical construct in physics that describes particles of matter and their interaction. Ex. Proton, Neutron, Electron etc.
• It is a description that views the elementary particles of the world as being connected by mathematical symmetries, just as an object and its mirror image are connected by a bilateral (left–right) symmetry.
• These are mathematical groups generated by continuous transformations from, say, one particle to another.
• According to this model there are a finite number of fundamental particles which are represented by the characteristic “eigen” states of these groups.
• The particles predicted by the model, such as the Z boson, have been seen in experiments and the last to be discovered, in 2012, was the Higgs boson which gives mass to the heavy particles.

Why is the standard model believed to be incomplete?

• The standard model is thought to be incomplete because it gives a unified picture of only three of the four fundamental forces of nature and it totally omits gravity.
• So, in the grand plan of unifying all forces so that a single equation would describe all the interactions of matter, the standard model was found to be lacking.
• The other gap in the standard model is that it does not include a description of dark matter particles.

How are the symmetries related to particles?

• The symmetries of the standard model are known as gauge symmetries, as they are generated by “gauge transformations” which are a set of continuous transformations (like rotation is a continuous transformation).
• Each symmetry is associated with a gauge boson.
• For example, the gauge boson associated with electromagnetic interactions is the photon.
• The gauge bosons associated with weak interactions are the W and Z bosons. There are two W bosons — W+ and W-.

What is the main result of the recent experiment?

• The recent experiment at CDF, which measured the mass of the W boson as 80,433.5 +/- 9.4 Mev/c2, which is approximately 80 times the mass of a hydrogen nucleus.
• This came out to be more than what is expected from the standard model.
• The expected value using the standard model is 80,357 +/- 8 MeV/c2 .
• Thus, the W boson mass itself is a prediction of the standard model.
• Therefore, any discrepancy in its mass means a lack of self-consistency in the standard model.

What is the discrepancy they obtained?

• The mass discrepancy of the W boson needs to be checked and confirmed to the same accuracy by other facilities, for example, the Large Hadron Collider (LHC).

Where do we stand now in terms of new physics?

• New physics is in the air, and experiments have been gearing up for some years now to detect new particles.
• With its high-precision determination of the W boson mass, the CDF has struck at the heart of the standard model.
• So it is a significant finding and if this is confirmed by the LHC and other experiments, it will throw open the field for ideas and experiment.

 

 

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The Union government has constituted an expert panel to probe the recent series of battery explosions in electric vehicles (EVs).

Why is the world poised to transition to electric vehicles?

• The growing concern over climate change has led to global efforts to electrify the transportation sector.
• In parallel, cost of Li-ion (Lithium-ion) battery technology has decreased by a staggering order of magnitude in the past decade.
• The convergence of these two factors has resulted in a unique time in our history where we are at the cusp of a dramatic transition in the transportation sector.
• There are multiple trade-offs in this complex ecosystem: engineering higher safety often results in higher costs and lower driving range.
• In this competitive landscape where companies are vying for market share, a race to the bottom can compromise safety.

A race to nowhere

• The world has taken note of this moment with governments providing incentives to usher in the transition and private industry ramping up plans for capturing the market.
• There is a worldwide race emerging, with vehicle companies, battery manufacturers, and material suppliers vying with each other for market share.
• However, Li-ion batteries are complex devices requiring a level of sophistication that can takes years to perfect.
• Hurrying the development of this complex technology without careful safeguards are leading to increasing safety incidents, as evidenced recently on Indian roads.

What goes into a Li-ion battery?

• Every Li-ion battery consists of three active components:

1. Anode: typically graphite
2. Cathode: based on a nickel, cobalt, and manganese-based oxide; and
3. Electrolyte: A salt of lithium in an inorganic solvent

• Battery cells are assembled into modules and then further assembled into packs.
• Li-ion batteries require tight control on the state of charge and the temperature of operation to enhance safety and increase usable life, achieved by adding multiple sensors.
• Packs are designed to ensure uniform temperature profile with minimal thermal variation during operation.

What is the level of precision involved?

• Battery manufacturing is a complex operation involving forming sheets of the anode and cathode and assembling them into a sandwich structure held apart by a thin separator.
• Separators, about 15 microns in thickness — about a fifth of the thickness of the human hair — perform the critical function of preventing the anode and cathode from shorting.
• Accidental shorting of the electrodes is a known cause of fires in Li-ion cells.
• It is important that the various layers are assembled with high precision with tight tolerances maintained throughout the manufacturing process.
• Safety features, such as thermal switches that turn off if the battery overheats, are added as the sandwich is packaged into a battery cell.

What causes battery fires?

• Battery fires, like other fires, occur due to the convergence of three parts of the “fire triangle”: heat, oxygen, and fuel.
• If an adverse event such as a short circuit occurs in the battery, the internal temperature can raise as the anode and cathode release their energy through the short.
• This, in turn, can lead to a series of reactions from the battery materials, especially the cathode, that release heat in an uncontrolled manner, along with oxygen.
• Such events also rupture the sealed battery further exposing the components to outside air and the second part of the fire triangle, namely, oxygen.
• The final component of the triangle is the liquid electrolyte, which is highly flammable and serves as a fuel.
• The combination leads to a catastrophic failure of the battery resulting in smoke, heat, and fire, released instantaneously and explosively.

What triggers battery fire?

• The trigger for such events can be a result of internal shorts (like a manufacturing defect that results in sharp objects penetrating the separator).
• The external events may be accident leading to puncture of the cell and shorting of the electrodes, overcharging the battery.
• Any of these triggers may cascade into a significant safety incident.

Are battery fires inevitable?

• Over the past three decades, Li-ion batteries have proved to be extremely safe, with the industry increasing controls as safety incidents have surfaced.
• Safety is a must and is an important consideration that battery and vehicle manufacturers can design for at multiple levels from the choice of battery material to designs at the cell, pack, and vehicle level.
• Protecting the cell with robust thermal management is critical, especially in India where ambient temperatures are high.
• Finally, battery packs need to be protected from external penetration.
• Any large-scale manufacturing process inevitably has a certain percentage of defects; therefore, such steps are needed to minimise the number of adverse events.

Why battery safety matters?

• Safety remains a concern for Li-ion manufacturers worldwide especially as cell sizes become larger for applications such as solar-connected storage.
• There is a need to remove the threat of battery fires as the roll out of mass electrification takes place.

 

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Amidst stiff resistance from Ukraine in the ongoing war and harsh sanctions imposed by the West, Russia went ahead and tested its new Inter Continental Ballistic Missile (ICBM) Sarmat.

What is Sarmat?

• The RS-28 Sarmat (NATO name Satan-II) is reported to be able to carry ten or more warheads and decoys
• It has the capability of firing over either of the earth’s poles with a range of 11,000 to 18,000 km.
• It is expected to pose a significant challenge to the ground-and-satellite-based radar tracking systems of the western powers, particularly the USA.
• The ten warheads are Multiple Independently-Targetable Re-entry Vehicles and each has a blast yield of .75 MT.
• The Sarmat will also be the first Russian missile which can carry smaller hypersonic boost-glide vehicles. These are manoeuvrable and hard to intercept.
• It is a liquid-fuelled missile as compared to US ICBMs which have moved on to solid fuel systems.

Who is it named after?

• The Sarmat is named after nomadic tribes that roamed the steppes of present-day Southern Russia, Ukraine and Kazakhstan in the early medieval period.
• Sarmatians were highly developed in horsemanship and warfare.
• It goes on to say that the administrative capabilities and political expertise of Sarmatians contributed to their gaining widespread influence and by the 5th century BC.
• They held control of the land between the Urals and the Don River.
• In the 4th century they crossed the Don and conquered the Scythians, replacing them as rulers of almost all of southern Russia by the 2nd century.

Was Russia known to be developing this missile?

• It was widely known that Russia was developing a new ICBM to replace its older ones.
• An announcement in this regard was made by Vladimir Putin in 2018 while making his State of the Nation address to the Federal Assembly.
• He had stated at the time that the first Regiment fully armed with Sarmat ICBM will be operational by the end of 2022.
• The deteriorating relations between Russia and the Western Powers is said to have given an impetus to its development.

 

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The global supply of semiconductors is now being threatened once again by the Ukraine crisis on account of supply of two key raw materials — neon and palladium — that are at a risk of being constrained.

What are Semiconductors?

• A semiconductor sits between a conductor and an insulator and is commonly used in the development of electronic chips, computing components, and devices.
• It’s generally created using silicon, germanium, and other pure elements.
• Semiconductors are created by adding impurities to the element.

Why are neon and palladium important for chipmaking?

(a) Neon

• Neon gas is used in the photolithography process that is the most common method for fabricating integrated circuits.
• Specifically, the neon gas is used in the laser machines that carve the integrated circuits.
• But for use of neon gas in the semiconductor industry, the gas has to reach 99.99% purity levels — which makes it a rarity.
• More than half of semiconductor-grade neon comes from Ukrainian companies Incas and Cryoin.

(b) Palladium

• It is used for multiple purposes in semiconductor and electronic manufacturing.
• It is used to coat electrodes that help control flow of electricity.
• It is also used in plating of microprocessors and printed circuit boards — which is an essential process of chip making.
• Russia accounts for nearly half the global supplies of palladium and the multiple trade sanctions on Moscow threaten to constrain the availability of the element.

Why was there a shortage in semiconductors?

• The trigger point was the beginning of the Covid-19 pandemic and the subsequent lockdowns across the world that forced chip-making facilities to shut in countries like Japan, South Korea, China and the US.
• A key feature in a chip shortage is that it almost always causes cascading effects, given that the first one creates pent-up demand that becomes the cause for the follow-up famine.

How is the Russia-Ukraine crisis protracting this shortage?

• Palladium and neon are two resources that are key to the production of semiconductor chips.
• Russia supplies over 40 per cent of world’s palladium and Ukraine produces 70 per cent of neon.

How long will the semiconductor shortage last?

• The answer to that question is a function of two variables:

1. Existing stockpiles of these raw materials with chip manufacturers
2. Time for which the crisis in Ukraine prevails

• If a deal is not brokered in the coming months, expect the chip shortage to get worse and for industries highly dependent on them to be similarly affected.
• This means significant risks are ahead for many automakers, electronic device manufacturers, phone makers, and many other sectors that are increasingly reliant on chips for their products to work.

 

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