The turnaround of the three physics questions I offered a few days ago, to stimulate your neurons and extract you from the chocolate and alcohol flood caused by the usual string of Christmas parties and dinners, was rather scarce. Despite that, I wish to repeat the offer today, making some adjustments to reach a wider public. The questions I offer here are easier but still not accessible to everybody. However, my plans are that at least the answers I will give in a couple of days will be understandable. Further, anyone can try the bonus question I ask at the bottom of this piece...
So below are three more questions on experimental high-energy physics, a bit more accessible than the previous ones. Please try them and report your answers below. The time you spend on the test will not be wasted!
1) The LHC experiments will search for Z bosons in their early 2010 data. The Z decay to muon pairs, in particular, provides a means to verify the correct alignment of tracking detectors and the precise modeling of the magnetic field inside the solenoid, which bends charged tracks traversing its volume.
If the signal cross section equals 50 nanobarns, and only three decays in a hundred produce muon pairs, calculate the integrated luminosity required to identify 100 candidates, assuming that the efficiency with which a muon is detected is 70%.
Hint: you will need to use the formula , and all the information provided above.
2) In the decay of stopped muons, , the produced electron is observed to have an energy spectrum peaking close to the maximum allowed value. What is this maximum value, and what causes the preferential decay to energetic electrons ?
Hint: you might find inspiration in the answer to the first question I posted on Dec. 26th.
3) The decay to an electron-neutrino pair of the W boson occurs one-ninth of the time, because the W may also decay to the other lepton pairs and to light quarks, and the universality of charged weak currents guarantees an equal treatment of all fermion pairs. The question is: if the W boson had a mass of 300 GeV, what would the rate of electron-neutrino decays ?
Hint: the top quark would play a role...
Bonus question: What do you get if you put together three sexy red quarks ?
Answers in a couple of days... Take your thinking hat and start working now!
- PHYSICAL SCIENCES
- EARTH SCIENCES
- LIFE SCIENCES
- SOCIAL SCIENCES
Subscribe to the newsletter
Stay in touch with the scientific world!
Know Science And Want To Write?
- How Gut Bacteria Ensure A Healthy Brain – and Could Play A Role In Treating Depression
- Researchers Created A Laser Bullet To See What It Would Look Like - And Here It Is
- The Strange Organic Molecules In Titan's Atmosphere
- We're Too Late To Prevent 137,000 More Ebola Cases, Says Epidemiology Paper
- The Quote Of The Week - Shocked And Disappointed
- Type 1 Diabetes Surges In White Kids
- It Takes More Than Singing To Strike A Chord In Music Education
- "I found the AMO/PDO charts to be very broad, and hard to tell (at least with the limited knowledge..."
- "I have dabbled with AMO and PDO, but it really needs to be more of a comparison to SST's, at which..."
- "The UN with it's small direct Ebola budget is hiring Ebola survivors to take care of sick kids..."
- "Ebola patients are sometimes thought of as Zombies returning from the dead. If one is low in fluids..."
- "In a universe of infinite realities, maybe there is one where homeopathy works. Just not in this..."
- Leftist dystopia? Anti-technology fever animates opposition to GMOs and other ‘disruptive’ technologies
- CDC faced a nearly impossible balancing act with Ebola, and failed
- Why Chobani reversed course, making yoghurt only from milk from cows not fed GMO grain
- Monterey, California, hotbed of anti-GMO activism, home to new GMO corn farm
- Evolution is sometimes messy or even outright ridiculous
- Rich and famous embrace Vandana Shiva, wealthy self-described savior of the poor