Hydrogen bubble chamber
HYDROGEN BUBBLE CHAMBER
QUESTION1: Estimatethe number of particle tracks that you can see in Figure 22.15.
Thefigure given shows a chamber where the paths left behind by theionized gas particles are approximately twenty-nine tracks. These arethe only clearly visible tracks though there may be more.
QUESTION2: Fromthe image of Figure 22.15, determine which way the magnetic fieldpoints: perpendicular or parallel to the image.
Thischamber is subjected to a constant magnetic field that causes thecharged particles to move in helical paths whose radius is usuallydetermined by their charge-to-mass ratios as well as theirvelocities. In the given diagram, the magnetic north and south polesare oriented in such a way that the magnetic field points directlyinto the page. This perpendicular direction of magnetic fields oncharged particles depends on the sign of the charge and the directionof motion.
QUESTION3: Identifyeach of the following types of tracks in Figure 22.15:
a.Atrack that looks straight.
Thestraight looking paths are left behind by the neutrally chargedparticles. These particles leave a straight track since they producevery little ionization. Consequently, their paths can be easilyinterfered by the tell-tale tracks present between the visible ones.
b. A track that spirals tightly (a small spiral) and a track that spirals loosely (a large spiral).
Therecurved tracks in this diagram. The difference in the degrees ofcurvature between different paths is as a result of the difference inmass, speed and charge of the particle. This causes theproportionality between the momentum of the particles and the radiusof the curves they leave behind.
c.Abright track and a fainter track
Someparticles also leave a fainter or a brighter track depending on theamount of charge in the particles.
d.Twotracks that form a "V" shape
Thetracks forming a “v” shape are left behind when a neutralparticle decays producing two oppositely charged electrons thatoriginate from the same point in different directions.
e.Atrack with an obvious beginning and ending
Thediagram also shows some tracks that have a definitely obviousbeginning and an obvious end. The particles that leave these tracksare neither positively nor negatively supercharged at a high speedthus making their paths more distinct.
f.Atrack with a kink, or abrupt change of direction
Someof the tracks also show a sudden change of direction due to collisionwith other charged particles. This may cause a transfer of energyfrom one particle to another thus causing a change in the charge ofthe particle. Since the direction of the path depends on the natureof the charge, a change in the ionization state of the particles mayconsequently cause a change in the direction of the paths.
QUESTION4: Whatcan you say about the velocity of particles that leave straighttracks?
Thevelocity of the particles has a little effect on the type of theirpaths because the curves depend on the nature of the charge.Neutrally charged particles leave behind a straight path irrespectiveof the speed.
QUESTION5: Considerthe tight spiral and the loose spiral tracks.
a. If both tracks were made by electrons, which particle was traveling faster?
Thehigh-speed charged electrons leave loose spirals while low-speedelectrons leave behind tight spirals. The high-charge particles leavea path radius that appears larger than the paths left out byelectrons.
b.Ifboth tracks were not made by electrons, what can you say about thetotal energy of each particle, including its mass?
Thetotal mass and charge energy of particles that leave tight or loosespirals that may be bright or fainted are usually very high.
QUESTION6: Considerthe bright track and the faint track.
a.Whichtrack shows the faster particle?
Brightnessor faintness of a particle depends on the time spent in the sameposition. High speed particles are likely to leave faint tracksbecause the time spent at a particular position is always veryminimal.
b. Now apply this reasoning to the tight and loose spiral tracks. Can you tell which particle was moving faster?
Fastmoving particles leave a loose spiral track compared to low-speedparticles which leave tighter tracks.
c.Ifthe looser track is also brighter, were both the loose and the tighttracks made by the same type of particle?
Whena loose track is brighter, this means that particle was travelling ata relatively slower speed compared to the particles that left a fainttrack.
QUESTION7:Ifthe two particles were a proton and an electron, but both arms of the"V" curved the same (possibly very small) amount, what canyou say about their relative velocities?
Ifa neutral particle decays producing a proton and a neutron, the pathsdiverge forming a v-shape. The similarity in the tightness andlooseness of the spirals show that the velocities of the twoelectrons are relatively the same.
QUESTION8: Atrack with an obvious beginning and endpoint shows an event initiatedby a neutral particle. Because neutral particles do not leave tracksin the chamber, this type of track must be a charged particle thatsuddenly begins moving. How might a neutral particle initiate one ofthese tracks?
Collisionof particles and subsequent transfer of energy cause the neutralparticles to initiate a motion leaving behind paths with a definitebeginning and a definite end.
QUESTION9: Akink occurs when a charged particle decays, emitting a particle andin the process becoming a different charged particle. Is the particleemitted in the decay neutral or charged? How do you know?. Does theremaining charged particle have more or less mass than before itdecayed?
Whena particle decays, it emits charged electrons that move eitherclockwise or anti-clockwise depending on their charge. This isbecause the decay of a particle results in electrons which must havea positive, negative, or a neutral charge. The particle remainingafter decay usually has a reduced mass due to the emission ofelectrons.
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