the tools used to detect (and sometimes) characterize ionizing radiation. This tag is appropriate for question about the characteristics and behavior of all such devices from the simplest Geiger-Muller tube, to the compound monsters used by high-energy experiments to the mega-ton instrumented volume ...

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28
votes
3answers
4k views

How can an electron fake a jet?

This is a question for experimentalists. I have seen in several ATLAS papers (see for example chapter 4 in arXiv:1602.09058, 6th paragraph), that after objects have been correctly identified, any jet ...
16
votes
4answers
3k views

How does one detect a single photon?

I understand the double slit experiment up until the point that we begin "detecting" single photons. What does it mean to detect. You cant place a camera in the slit because that would capture the ...
13
votes
1answer
565 views

Operator that describes particle detector

In non-relativistic QM, the position of a particle is an observable. In QFT, fields are the observables. However, particles must have some sort of position, otherwise we wouldn't see pictures like the ...
10
votes
2answers
8k views

What is $p_T$? (transverse momentum?)

I've been looking at a few papers in experimental physics (from the ATLAS collaboration, for example) and I've often run across phrases such as "high-$p_T$ electron." What exactly is $p_T$? Is it ...
9
votes
2answers
4k views

Which is the smallest known particle that scientists have actually *seen with their eyes*? [closed]

Which is the smallest particle that has been actually seen by the scientists? When I say "actually seen", (may be using some ultra advanced microscope or any other man made eye, using any wavelength ...
9
votes
2answers
833 views

How do tracking detectors in particle accelerators create the pretty pictures we see?

I have read several sources about tracking detectors used in particle accelerators like LHC, but still have not found a more detailed source that can still be understood by a layperson like myself. I ...
9
votes
2answers
956 views

What does the data in various stages of analysis from a particle collision look like?

I've been following the news around the work they are doing at the LHC particle accelerator in CERN. I am wondering what the raw data that is used to visualize the collisions looks like. Maybe someone ...
8
votes
2answers
932 views

Does a muon detector on Earth's surface correctly measure the mean lifetime of a muon?

Just a simple question. Does a muon detector on Earth's surface correctly measure the mean lifetime of a muon? I would think the answer is no because most muons detected are created about 15 km above ...
8
votes
1answer
437 views

How to distinguish high-energetic muons and electrons in the CMS and ATLAS muon detectors?

At a typical energy of about 100 GeV, a muon has a Lorentz factor of about 1000, an electron about 200.000. The flight time to the detector should be around 30 ns (assuming d= 10m from the collision ...
7
votes
1answer
343 views

Is it feasible to measure the energy of cosmic ray muons with a consumer Digital Single Lens Reflex camera?

I have read this article SIBBERNSEN, Kendra. Catching Cosmic Rays with a DSLR. Astronomy Education Review, 2010, 9: 010111. and it talks about estimating the muon cosmic ray flux by means of a DSLR ...
7
votes
3answers
754 views

Fiducial volume in collider/detector physics

I'm trying to make some sense of ATLAS measurements for a personal project to learn how to use Pythia, and part of my work requires me to recreate the distribution for Z boson decay. I encountered the ...
6
votes
7answers
380 views

Effect of wavelength on photon detection

When some photon detector detects a photon, is it an instantaneous process (because a photon can be thought of as a point particle), or does the detection require a finite amount of time depending on ...
6
votes
2answers
140 views

Deciding what to collide at particle accelerator

Different particle accelerators use different types of collisions. For instance at the LHC they investigated p Pb collisions while its predecessor (LEP), used to collide electrons with proton and at ...
6
votes
1answer
227 views

Measuring nucleons using electron beams

sorry if the question is too elementary. From: The Britannica Guide to Particle Physics: The sizes of atoms, nuclei, and nucleons are measured by firing a beam of electrons at an appropriate target. ...
6
votes
1answer
630 views

7 GeV dark matter particle: how particle accelerators missed it?

This posting is regarding the recent confirmation of the DAMA results that might be due to underlying differences in proton and neutron cross section with the dark matter particles, which reflect on ...
5
votes
1answer
1k views

Neutrinos arrived before the photons (supernova)

A while back I read about the super Kamiokande detector detected a large neutrino flux and then several hours later a supernova was seen. Anyone know of this with sources? I don't recall the source at ...
5
votes
1answer
400 views

What is the smallest distance between a decaying vertex and an interaction point a detector can measure?

A short lived particle is created at the interaction point and then decaying a distance $d$ away, in some detector. My question is what is the smallest distance $d$ that can be measured experimentally?...
5
votes
1answer
46 views

Ideas for extending Muon-Life-Time experiment?

Background: I'm teaching a lab experiment for measuring the Muon lifetime. The experiment is a big tube of scintillator attached to a PMT. The muon entering the scintillator generates a reading in the ...
4
votes
3answers
580 views

Does a Photon leave trace in a silicon tracker?

I am having this image from ATLAS Detector. In gray you can see the ATLAS's Si Tracker.In Green you see the Electromagnetic Callorimeter. In red there is the Hadron Callorimeter and in Blue there ...
4
votes
2answers
799 views

Energy measurement of W- and Z- bosons

W bosons decay into an electron and electron-neutrino or into a muon and muon-neutrino. The W lifetime is about $3 \cdot 10^{-25} s$, that means the decay occurs close to the collision point, not in ...
4
votes
3answers
427 views

How can a detector distinguish between a photon and a gluon

Considering that both gluons and photons have no mass, no charge and spin 1, I was wondering how one can tell the difference, if they hit a detector after a collision at the LHC. I know that gluons ...
4
votes
1answer
169 views

How use the Higgs branching ratio plot to extract information about the Higgs mass compared to experiment?

What does the plot of higgs branching ratio (see figure below) say about the higgs mass anyway? How can one use it as a guide to find the higgs mass experimentally? If we e.g. go to $M_H=126$ GeV (...
4
votes
2answers
144 views

Is a DIY neutrino detector feasible?

How long does a neutrino detector filled with distilled water need to be to pick up neutrinos from one direction at about the level of a distant star within our galaxy? Would an off the shelf ...
4
votes
1answer
45 views

Is it possible to use hot cloudy water as a cloud chamber?

This morning I got some warm water from the shower head to a dark plastic basin to wash some sensitive clothes. During the process lots of tiny bubbles got into the water so it had a cloudy ...
4
votes
1answer
83 views

Rejecting background in $B$-meson decay

I want to reconstruct the $B$ mass from the decay $$ B^0 \rightarrow K^{0*} \gamma \quad\text{ where }\quad K^{0*} \rightarrow K^{+} \pi^{-} $$ and the equivalent antiparticle decay. A key element in ...
4
votes
1answer
122 views

Proton flux model or data at energy range up to 100 keV

I am looking for a model or at best the database of proton fluxes (solar p+) at a energy range of some eV up to 100 keV. I have already found the SOHO database: http://umtof.umd.edu/pm/ But the ...
3
votes
1answer
69 views

How does a noseblow counter detect alpha radiation?

After working in air fed suits,operatives are required to give samples from their nasal passages by blowing their nose into a tissue,which is then counted in a noseblow counter. How does this work?
3
votes
1answer
156 views

Why apply voltage on an Si detector only on atmosphere or high vacuum

The general instruction when using a silicon detector is to either apply voltage only in atmospheric pressure or in high vacuum. Not in between! I can't find a physical answer to it. Why is it so ...
3
votes
1answer
4k views

What is Transverse Energy?

What is transverse energy? Why we use transverse total energy instead of energy and transverse momentum in place of Total momentum in the particle detectors?
3
votes
1answer
337 views

What algorithms are used for track reconstruction in cloud chambers?

In particular I'm interested in any algorithms that can separate multiple tracks from one another reliably.
3
votes
1answer
307 views

Cloud chamber video showing large particles - What are they?

Watching a video of a cloud chamber on wikipedia (http://en.wikipedia.org/wiki/File:Cloud_chamber.ogg), I cannot help noticing the large collisions that take place at 00:12 and 00:24. What are they?...
3
votes
1answer
1k views

How to measure (missing) transverse energy

There is traditionally a bit of confusion between missing transverse energy, and missing transverse momentum. I've seen both used interchangably, and sometimes even things like "$\not E_T = -|\sum \...
3
votes
1answer
518 views

Explain background pattern in particle tracing image

I'm trying to understand this image of a particle tracing experiment (which can be found all over the net if you google for "bubble chamber"): ( There are two things that I can't figure out: The ...
3
votes
1answer
79 views

Single electron non-perturbing detector

I am designing an experiment where I need to trigger the release of an electron by a radioactive source (Sr-90). The easy way to do it is to use a thin scintillator right after the source collimator. ...
3
votes
0answers
27 views

Detection of radioactive iodine at trash dumps [closed]

I have a cat that is getting radioactive iodine therapy and I am told I must flush the litter for 2 weeks because if I throw it away normally the dump will detect the radiation and fine me. This ...
3
votes
0answers
44 views

Sensitivity of Cloud Chamber

I have been watching some videos on cloud chambers: https://www.youtube.com/watch?v=Efgy1bV2aQo and they are quite amazing. What I can't figure out, is why aren't these chambers over loaded with ...
3
votes
0answers
273 views

What does it take to recreate double slit experiment with detectors?

Is there anyway to recreate this experiment with detectors at home? I want detectors because I want to get non interference pattern too. I have a little know-how in electronics so If I need to buy a ...
3
votes
0answers
62 views

Alternative ways to take particle tracks photographs in a cloud chamber

I know that the most common type of particle tracks photography is in photographic plates, but i'm using a cloud chamber and I would like to know if there are alternative ways to take photographs of ...
2
votes
3answers
305 views

Detecting negative energy products in particle accelerators

Are the detectors in a typical particle accelerator experiment, either in Fermilab, or now in LHC, sensitive to negative energy particles? How would a negative energy particle, (say, a negative ...
2
votes
3answers
154 views

New physics at high energies, cosmic rays, particle-detectors in space

New physics is expected at high energies and cosmic rays have high energies, so have there been or are there any plans to put particle detectors in space to study cosmic rays for new physics ?
2
votes
2answers
1k views

How are quarks and leptons detected experimentally?

How are quarks and leptons (including subatomic particles) detected in the laboratory,especially when most hadrons and leptons have a lifespan for a considerable small amount of time?Also how do we ...
2
votes
1answer
55 views

How doesn't an ionization chamber leak?

I'm sure my understanding of an ionization chamber is incorrect, so please point out the error. Suppose we are using an sealed ionization chamber to detect the energies (trajectories) of a particular ...
2
votes
2answers
175 views

CERN projects on gravity

Recently I was reading about CERN's upgrade to work on gravitational theories. But if most of the work has been done by General Theory of Relativity than with other theories are there that need to be ...
2
votes
1answer
102 views

Why, in particle physcis experiments, the background is sometimes a decaying exponential?

Take, as an example, the Higgs boson finding: But the same is found in many other particle physics detector graphs... **Why is the shape of the background a decaying exponential? ** At least ...
2
votes
1answer
108 views

Why Microchannel Plates can be operated only in vacuum?

Why it is said that the Microchannel Plates can be operated in vacuum? What is the maximum pressure in which it can be operated? Also, while it is not operating, should it be kept in vacuum? Is this ...
2
votes
2answers
237 views

Reference for solid state particle detector

I'm looking for a good introductory text on solid state devices for particle detection.
2
votes
1answer
181 views

How do micro-channel plates detect neutral molecules?

Micro-channel plate (MCP) detectors are used to detect photons, electrons or charged particles. But how can MCPs be used to detect neutral particles? In ion traps, the neutral molecules (after being ...
2
votes
1answer
123 views

experimental setup to measure Center-Of-Momenta of products from spontaneous radiactive decay

This question is an attempt to complement this other question about fluctuations in radiactive decay. This question is completely experimental though: in general, suppose i have certain sample of a ...
2
votes
1answer
51 views

“Double-counting” in particle detectors

Apparently, when analysing events from particle detectors, one may incur in double-counting, which happens when a physics object appears as a single object of its own type, but it may also be ...
2
votes
1answer
273 views

Understanding how mass spectroscopy works

Let me start by saying that I've posted this question here as well. I've posted it here because I think the questions I've asked involve the physics of molecules. So I’m trying to get a deeper ...