Half-life of Barium

Nuclear decay is a random process, yet it proceeds in a predictable fashion. To resolve this paradox, consider an everyday analogy. An unstable nucleus in a sample of radioactive material is like a popcorn kernel in a batch of popcorn that is being heated. When a kernel pops, it changes form. Similarly, an unstable nucleus changes form when it decays. 

It is practically impossible to predict which particular kernel will pop at any given instant, and in this way the popping of corn is a random process, much like radioactive decay. However, the cornpopping process is predictable in the sense that you can say how much time it will take to prepare a batch of popcorn. Similarly, a sample of radioactive material decays within a known time period. This period is called a half-life. 

The half-life of a radioactive species is defined as the time it takes for the activity of the sample to drop by 50%. In this activity, you will investigate the decay of 137Bam, a metastable isotope of barium that undergoes gamma decay with a half-life of several minutes. 

Read over the entire laboratory activity. Hypothesize how the activity of the 137Bam sample will behave. Record your hypothesis in the next column. 

Connect the detector-counter apparatus by following the directions given by your teacher. Switch the apparatus on. 

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Barium-140 (tl/2 = 12.8 d) released in the fire at the Chernobyl nuclear plant has been found in some agricultural products in the region. The biological half-life of barium-140 in the human body is 65 d. What is the effective half-life (see Exercise 17.55) of barium-140 ... 

Barium-131 is a radioisotope used to study bone formation. A patient ingested barium-131. How much time will elapse until only one-fourth of the barium-131 remains, assuming that none of the isotope is eliminated from the body through normal processes The half-life of barium-131 is 11.6 minutes. 

Radium is chemically similar to barium it displays a characteristic optical spectrum its salts exhibit phosphorescence in the dark, a continual evolution of heat taking place sufficient in amount to raise the temperature of 100 times its own weight of water 1°C every hour and many remarkable physical and physiological changes have been produced. Radium shows radioactivity a million times greater than an equal weight of uranium and. unlike polonium, suffers no measurable loss of radioactivity over a short period of time (its half life is 1620 years). From solutions of radium salts, there is separable a radioactive gas radium emanation, radon, which is a chemically ineit gas similai to xenon and disintegrates with a half life of 3.82 days, with the simultaneous formation of another radioactive element, Radium A (polonium-218). 

The NAA method for the determination of firearm discharge residue has been generally accepted, but applications have been limited to just a few laboratories. In the process of establishing NAA capability for the State of Illinois crime laboratories we re-examined the standard techniques (10). In the course of our work it became clear that post-irradiation is the cause of several constraints which have discouraged a more widespread use of NAA. The inherent time limitation due to the 87 min. half-life of 139Ba necessitates fast manipulations of radioactive solutions which in turn requires an experienced radiochemist. In addition to an ever present danger of overexposure and contamination, typically only a dozen samples can be irradiated per batch, which makes the method quite expensive. The developed statistical bivariate-normal analysis (11) is convenient for routine applications. With this in mind, a method was developed which a) eliminates post-irradiation radiochemistry and thus maximizes time for analysis b) accommodates over 130 samples per irradiation capsule (rabbit) c) does not require a collection of occupational handblanks and d) utilizes a simplified statistical concept based on natural antimony and barium levels on hands for the interpretation of data. The detailed procedure will be published elsewhere (15). 

The case of 228Ra is simpler than that in Example 1. Although the half life of 228Ac requires a 2-day interval to exceed 99% of equilibrium, no delay is needed because 228Ac also is co-precipitated with barium sulfate, so that initial radioactive equilibrium within the precipitate remains undisturbed. 

Ds refers to the 228Ac half-life of 6.15 h, but parent and daughter are in equilibrium (Ds = 1.00) immediately because both are co-precipitated with barium sulfate. 

The source of the y-rays is the 119mSn isotope which is prepared by the (n,y) reaction of 118Sn. It decays with a half life of 245 days to give the nuclear excited 119Sn. This has a spin / of /2, and a half life of 1.84 x 10 x s, and emits ay-ray of 23.875 keV in its transition to the ground state with spin I of 1 /2. It is usually incorporated into barium or calcium stannate, which give a line-width of about 0.33 mm s 4. Measurements are usually carried out at 77 K, to increase the recoil-free fraction of the emission and absorption for BaSnC>3, this is 0.8 at 77 K, and 0.55 at 300 K. 

Barium plumbate is electrochemically stable in the positive plate. Chemically, however, it can be slowly attacked by dilute sulfuric acid. The first-order rate constant for decomposition of barium plumbate in dilute sulfuric acid was determined to be A = 2.6 x 10 " H exp (-EJRT), where is 31.6 kcal, R is the gas constant, and T is the absolute temperature. The half-life of this material in... 

Cesium, as well as cesium-137, is a soft, malleable, silvery while metal. Cesium is one of only three metals that is a liquid near room temperature (83 F). The half-life of cesium-137 is 30 years. It decays by emission of a beta particle and gamma rays to barium-137m. 

Cesium-137 undergoes radioactive decay with the emission of beta particles and relatively strong gamma radiation. Cesium-137 decays to barium-137m, a short-lived decay product, which in turn decays to a nonradioactive form of barium. The half-life of cesium-137 is 30.17 years. Because of the chemical nature of cesium, it moves easily through the environment. This makes the cleanup of cesium-137 difficult. 

CaS04 2 H2O) in plasters to decorate their tombs. These two alkaline earths are among the most abundant elements in the Earth s crust (calcium is fifth and magnesium sixth, by mass), and they occur in a wide variety of minerals. Strontium and barium are less abundant but like magnesium and calcium, they commonly occur as sulfates and carbonates in their mineral deposits. Beryllium is fifth in abundance of the alkaline earths and is obtained primarily from the mineral beryl, 863 2(8103)6. All radium isotopes are radioactive (the longest lived isotope is Ra, with a half-life of 1600 years). Pierre and Marie Curie first isolated radium from the uranium ore pitchblende in 1898. Physical properties of the alkaline earths are given in Table 8.4. 

During the operation of the neutronic reactor particularly at high neutron densities radioactive elements of exceedingly high capture cross section may be formed in the uranium as an intermediate element in the decay chains of fission fragments and this formation will lower the value cf the reproduction factor for the system. Radioactive xenon is an example of such an intermediate element, this product having a half life of about 9 hours and being formed mostly from radioactive iodine which has a half life of about 6.6 hours and decays to barium. There should be sufficient excess In the reproduction ratio of the reactor so that in the event the re-... 

As regards water analysis, it should also be noted that barium isotopes may be present, in particular barium 140 which has a half-life of 12.8 days and is both a B -and a emitter. 

The daughter product resulting from the B" decay of barium 140 is lanthanum 140 which, with a half-life of roughly 40 hours, becomes inactive Cer-140. Like barium 140, lanthanum 140 is both a B"-and a -emitter. 

Many salts of the alkaline earth metals are insoluble and this feature is enhanced in the case of barium. Barium is less electronegative than calcium and it is less likely to form cationic complexes. One radioisotope exists, i.e., °Ba with a half-life of 12.8 days. 

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