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7 Be (T 1/2 = 54 days, E γ = 478 keV) is formed in the upper layers of the atmosphere in reactions where cosmic rays split nitrogen and oxygen atoms. The 7 Be ions formed attach to dust and aerosol particles and fall together with them onto the Earth's surface [1]. We present below the results of γ-spectrometric studies of the activity of 7 Be (N) in monthly (m) atmospheric fallout in the period 2004-2005 in Samarkand and compare these data with the amount of precipitation, average humidity, and average air temperature (data from the Samarkand regional hydrometeorological office).The atmospheric fallout samples were obtained as follows. A 100 × 100 cm and 10 cm high Duralumin vessel, whose bottom was smeared with 100 g of glycerin and covered with a layer of gauze, was exposed monthly on the roof of an 8 m high building. After the exposure was completed, the gauze we removed from the vessel. Any rain water or snow present in the vessel was evaporated to volume ≤100 ml, and the vessel was carefully wiped clean with fresh gauze.Two types of samples were prepared successively from the atmospheric fallout:• the gauze was allowed to dry (samples G with mass 180-230 g) and then folded into strips and neatly packed into one-liter Marinelli vessels; • after the samples G were measured, the gauze was removed from the Marinelli vessels, placed in a porcelain cup, and calcined in a muffle furnace (≤400 °C); the ash was packed into a 40 × 40 mm polyethylene packet (samples A with mass ∼8-25 g). Inert samples, prepared by the methods indicated above from 1 m 2 clean (unexposed) gauze, were used to determine the background component in the spectra of the experimental samples.The γ-ray spectra of the samples were measured with a 63 × 63 mm NaI(Tl) scintillation crystal and a 100 cm 3 Ge(Li) detector with resolution ∆E γ /E γ ≈ 10% and ∆E γ = 6.7 keV, respectively, on the 1332 keV 60 Co line, which were placed inside lead shielding with 10 cm thick walls. The MARS (JINR, Dubna) computer program was used for acquisition and processing of the spectra. The duration of individual measurements was 2-6 h.The γ-ray spectrometers were calibrated with respect to detection efficiency using 226 Ra, 232 Th, 40 K, and 137 Cs from the OMASN system (for the G samples) and 241 Am, 22 Na, and 137 Cs from the OSGI system (for the A samples).A dominant contribution from the background radiation to the intensity was observed, together with contributions from 7 Be and 226 Ra, 232 Th, and 40 K of natural origin, in the instrumental spectra of the samples. In the semiconductor spectra of the samples which were (Fig. 1) and were not (Fig. 2) calcined, the 478 keV 7 Be total absorption peak is well resolved

7 Be fallout measurements performed around Samarkand in 2002-2009 included in this research covers the ascending part of the 23rd solar activity cycle; this part of the cycle corresponded to a decrease of the monthly average value of the Wolf number from 60 to <5. The linear correlation observed between the fallout and amount of wet precipitation indicates that the latter plays the main role in the removal of 7 Be from the troposphere. The average seasonal 7 Be fallout is 223 ± 46 Bq/m 2 during winter, 324 ± 66 Bq/m 2 during spring, 75 ± 29 Bq/m 2 during summer, and 189 ± 43 Bq/m 2 during fall. These measurements make it possible to evaluate the contribution of precipitation in the form of dust and dew to the total 7 Be fallout during the summer. The correlation between the solar radiation and 7 Be fallout is confirmed.Cosmogenic 7 Be (T 1/2 = 54 days) is formed in the upper layers of the Earth's atmosphere in cosmic-ray induced fission of nitrogen and oxygen nuclei. The amount of 7 Be formed and reaching the Earth's surface depends on the intensity of the cosmic radiation [1], exchange processes occurring in the upper and lower layers of the atmosphere [2], and local climatic conditions. The possibility of detection in natural objects by γ-spectrometry makes cosmogenic 7 Be an indicator of processes occurring in the atmosphere [3][4][5] and surface layers of the soil (erosion and increase of deposits in water reservoirs). For effective use as an indicator of natural processes, the main regularities of local 7 Be fallout must be determined.This article presents measurements of 7 Be fallout performed around Samarkand (39°39′ N, 65°57′ E, 702 m above sea level) in 2002-2009. The calendar period included in this research covers the ascending part of the 23rd solar cycle, corresponding to the average-monthly value of the Wolf number -an index of solar activity -decreasing from 60 to <5 [6] (Fig. 1).Measurement Procedure. The 7 Be fallout occurring together with atmospheric precipitation was collected on gauze with area 1 m 2 permeated beforehand with glycerin and placed in a vessel of appropriate size. An open area located 8 m above ground was chosen for the exposure. 7 Be was collected in parallel in two vessels: one was a stationary vessel placed at the center of the area and the other one was moved periodically. The exposed samples were removed once a month. Prior to the measurements the gauze was dried and packed in a Marinelli vessel. Wet precipitation in the form of water drops or snow remaining in the vessels at the moment of sampling were evaporated at 70-80°C to a dry state and then included in the measurements.The 7 Be activity in the samples was determined from measurements of the intensity of the 478 keV γ-line performed with a 63 × 63 mm NaI(Tl) scintillator and a semiconductor ultrapure germanium γ-spectrometer with energy resolution

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Mines, works, water rock-crushing mills, furnaces for smelting of metals (gold, silver, lead, copper, zinc, mercury, iron), and fields of slag dumps dating from the 1st through the 19th centuries have been found in more than 50 places in the Chatkalo-Kuraminskii mining district (Tashkent Oasis) [1].The goal of the present work is to determine the specific activity of natural radionuclides in the uranium-thorium families and 40 K and to establish the elemental composition in samples of slag taken from dumps in the basins of the Bashkyzylsai River and its tributary, the Kyzylalmasai in the foothills of the Chatkal range, dating to the 5-7th centuries and from tributaries of the Akhangaran-Karabau and Karasarai Rivers in the foothills of the Kuraminskii Range, dating to the 11-12th centuries. The radionuclide composition of the samples was determined by γ-ray spectroscopy and the elemental composition, by neutron activation and x-ray spectral analysis.Two forms of samples were taken by quartering: vitrified slag in the form of solidified streams with smooth surfaces (initially extracted from the bottom of a smelter furnace) and slag with a porous structure formed on a molten metal surface. The color of the slag varied from black to dark gray. The overall number of samples was 27, each with a mass of 2 kg. The samples were first ground up in a agate mortar to a powder with a grain size of ≤10 µm and packaged in polyethylene bags. Samples with a mass of 1.5 kg, ground to a grain size of 5 mm and packed in sealed, one-liter Marinelli vessels, were used for the γ spectroscopy studies. The 50-mg samples for neutron activation analysis were packed in polyethylene bags and samples for x-ray spectroscopic analysis were prepared by drying 500 mg ground samples in vacuum and then adding 50 mg of boric acid. Samples in the form of 10 × 2 mm tablets were prepared by pressing (3 tons/cm 2 ) the carefully blended mixture.The radioactivity of the samples was measured in a Marinelli geometry using a scintillation gamma-ray spectrometer equipped with a 63 × 63 mm NaI(Tl) crystal (10% energy resolution at the E γ = 661 keV 137 Co line) and mounted in a lead box with 10-cm-thick walls. The γ-ray spectrum of each sample was accumulated over a period of 6 h. The instrument