I know that lead blocks X-rays but what about gamma rays?

Answer 1

gamma rays have waaaay too much energy in them, and youd need something much denser and heavier than lead to block it out

Answer 2

Does Lead Block X Rays

Answer 3

Gamma rays and X-rays are pretty much the same thing. Both are ionizing electromagnetic radiations. The only difference between them is the exact energy/ frequency/ wavelength of the radiation in question. the higher the energy, the greater the penetrating power.

X-rays generally are in the energy range of 0.1 kilo electron volts (keV) (soft X-rays) to 100 keV, while gamma rays are in the range of 10 keV (soft gamma) to 10 mega electron volts (MeV) (hard gamma). (1 MeV = 1000 keV)

Cosmic rays are also classified as in the gamma region (1 - 100 MeV). These are extremely penetrating, and will pass through the earth without even noticing that we're here.

Most of the gamma rays you'll encounter in your lifetime will be in the high X-ray/ soft gamma region, and sufficient lead/ concrete/ earth/ etc. will shield them quite adequately. We're exposed to very low levels of gamma rays all the time due to natural background radiation. If you take four 5-hour cross-country flights in a modern jet, you receive a total cumulative gamma/cosmic radiation dose approximately equivalent to a weak medical chest X-ray (~10 millirems).

So your answer really depends on exactly which energy-region gamma rays you are talking about!

Answer 4

"Protection from gamma rays can be obtained using a sheet of iron that is a 1/2 inch thick. This kind of shielding will block only 50% of 1 million electron volts of gamma rays. We can also protect ourselves from gamma rays with 4 inches of water. Lead provides the most protection from gamma rays. A 1/4 of an inch lead absorbs all the gamma ray exposure."

http://www.smgaels.org/physics/gamm_1.htm

"Very dense materials, such as lead, are commonly used as shielding to slow or stop gamma photons."

http://www.stoller-eser.com/Quarterlies/gamma.htm

"Thick materials such as lead, steel, or concrete are used for shielding gamma rays and x-rays."

http://www.pantex.com/ds/pxradc1a.htm

"Lead and other high-mass density materials are also good shielding materials for gamma radiation. Gamma radiation is the same type of radiation as x rays (called electromagnetic radiation); it may differ significantly in energy from some x rays, but the same kinds of materials effective against x rays are also good for gamma rays."

http://hps.org/publicinformation/ate/q1094.html

Answer 5

Gamma rays just pass right through lead. That's why radiographers in nuclear medicine don't wear lead aprons as the gamma rays have no lasting effect as they all simply pass straight through the body. To stop gamma rays you need material such as concrete or of similar density.

The pinickerty answerer's below are just daft. Yes if you had a piece of lead 4 miles thick I'm pretty sure it would stop any form of radiation, however a general rule is that lead may attenuate gamma rays slightly but it obviously depends on thickness, therefore when designing material to protect against gamma rays a mixture of concrete base is often needed or none at all. I work with it every week unlike the wikipedia fans below.

EDIT: Yeah I hate wikipedia answers they just annoy me. If you take any stock in their answers then you can also suggest that lead wouldn't stop x-rays. Whilst 2mm of lead is often considered sufficient, then If you reduced the density of the lead and increased the energy of the x-rays then it wouldn't be enough would it. I thought the varying thickness wouldn't have needed saying

Answer 6

Does depend a bit on your definition of x-rays and gamma rays. They are both electromagnetic radiation (photons) and sometimes defined over certain wavelength or energy ranges. Another common way of describing a definition is to say that x-rays are produced by a machine whereas gamma rays are emitted by the nucleus during a nuclear transformation. Under this definition a medical linac can produce x-rays ranging up to 20 MeV (with a spectral peak around 6 MeV) and some isotopes produce gamma rays around 20 keV.

Data for Lead from 20 keV to 20 MeV

Energy (MeV) mass-atten mass-energy
cm^2/g
2.00000E-02 8.636E+01 6.899E+01
3.00000E-02 3.032E+01 2.536E+01
4.00000E-02 1.436E+01 1.211E+01
5.00000E-02 8.041E+00 6.740E+00
6.00000E-02 5.021E+00 4.149E+00
8.00000E-02 2.419E+00 1.916E+00
8.80045E-02 1.910E+00 1.482E+00
K 8.80045E-02 7.683E+00 2.160E+00
1.00000E-01 5.549E+00 1.976E+00
1.50000E-01 2.014E+00 1.056E+00
2.00000E-01 9.985E-01 5.870E-01
3.00000E-01 4.031E-01 2.455E-01
4.00000E-01 2.323E-01 1.370E-01
5.00000E-01 1.614E-01 9.128E-02
6.00000E-01 1.248E-01 6.819E-02
8.00000E-01 8.870E-02 4.644E-02
1.00000E+00 7.102E-02 3.654E-02
1.25000E+00 5.876E-02 2.988E-02
1.50000E+00 5.222E-02 2.640E-02
2.00000E+00 4.606E-02 2.360E-02
3.00000E+00 4.234E-02 2.322E-02
4.00000E+00 4.197E-02 2.449E-02
5.00000E+00 4.272E-02 2.600E-02
6.00000E+00 4.391E-02 2.744E-02
8.00000E+00 4.675E-02 2.989E-02
1.00000E+01 4.972E-02 3.181E-02
1.50000E+01 5.658E-02 3.478E-02
2.00000E+01 6.206E-02 3.595E-02

Data for Ordinary Concrete from 20 keV to 20 MeV
Energy (MeV) mass-atten mass-energy
cm^2/g
2.00000E-02 2.806E+00 2.462E+00
3.00000E-02 9.601E-01 7.157E-01
4.00000E-02 5.058E-01 2.995E-01
5.00000E-02 3.412E-01 1.563E-01
6.00000E-02 2.660E-01 9.554E-02
8.00000E-02 2.014E-01 5.050E-02
1.00000E-01 1.738E-01 3.649E-02
1.50000E-01 1.436E-01 2.897E-02
2.00000E-01 1.282E-01 2.868E-02
3.00000E-01 1.097E-01 2.969E-02
4.00000E-01 9.783E-02 3.024E-02
5.00000E-01 8.915E-02 3.033E-02
6.00000E-01 8.236E-02 3.015E-02
8.00000E-01 7.227E-02 2.940E-02
1.00000E+00 6.495E-02 2.843E-02
1.25000E+00 5.807E-02 2.716E-02
1.50000E+00 5.288E-02 2.595E-02
2.00000E+00 4.557E-02 2.395E-02
3.00000E+00 3.701E-02 2.120E-02
4.00000E+00 3.217E-02 1.951E-02
5.00000E+00 2.908E-02 1.840E-02
6.00000E+00 2.697E-02 1.763E-02
8.00000E+00 2.432E-02 1.669E-02
1.00000E+01 2.278E-02 1.617E-02
1.50000E+01 2.096E-02 1.559E-02
2.00000E+01 2.030E-02 1.539E-02

You have to multiply these data by the relevant densities (in g/cm^3) to recover the attenuation or absorption co-efficient (mu or mu sub en) in cm^-1.

Lead: 11.35 g/cm^3
Ordinary Concrete: 2.3 g/cm^3

At 40 keV (an energy near the peak of a typical diagnostic x-ray spectrum) the attenuation co-efficient for lead is 163 cm^-1 and for concrete is 1.16 cm^-1. Thus 0.6 mm of lead will cut the intensity of the x-rays by a factor of about 20,000. It would take about 9 cm of concrete to achieve the same outcome.

At 20 MeV the attenuation co-efficient for lead is 0.7 cm^-1 and that for concrete is 0.053 cm^-1. 60 cm (about 2 feet) of concrete will cut the intensity by a factor of about 20, around 4.5 cm of lead should do the same.

These are narrow-beam attenuations, broad beam attenuation is less (sometimes the mu sub en co-efficient is used to estimate broad beam attenuation).

Choice of shielding material for a particular application depends on a number of factors including cost, availability, structural uses and loads and so-on.

Check out NCRP 147 for more than you'd ever want to know on how to design shielding. :-)

Answer 7

According to Wikipedia, yes lead can block gamma rays.

Answer 8

Gamma rays are more penetrating than x rays, they will go deeper into lead but they will be blocked if the lead is thick enough. Neutrinos, on average can penetrate light years thick lead.

Answer 9

lead can block gamma rays up to a point but you need a thick layer of it. A lead/concrete mix is best.
Gamma rays isn't as dangerous to human flesh as alpha and beta particles as it is non-ionising.

Answer 10

gamma yes