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A novel metastable phase of DyGe2.85 synthesised in the AuCu3-structure under high pressure, has been studied by means of the magnetic susceptibility and electrical resistivity measurements (under the pressure P ≤ 3.1 GPa), neutron powder diffraction and time-differential γ-γ perturbed angular correlations (TDPAC) using 111Cd nuclear probes. Two distinct phase transitions have been found in this compound as the temperature is lowered. We assign the first transition occurring at the temperature T CDW = 80 K with charge density wave formation and the second transition at T N ≈ 18 K with an antiferromagnetic spiral ordering of Dy magnetic moments, and discuss a close relationship between them.

The principal aspects of 44Ti application in time-differential γγ perturbed-angular-correlation method (TDPAC) for studying condensed matter are discussed. In the presented spectrometer modification, the efficiency of 44Ti application can be considerably increased by using thin NaI scintillator crystals. Promising techniques for 44Ti production and a method for synthesizing samples are described. Examples of TDPAC studies of titanium (rutile TiO2) and scandium (Sc2O3) oxide samples are shown.

We have used the time differential perturbed angular correlation (TDPAC) spectroscopy to measure the electric and magnetic hyperfine fields in RhGe crystallized in the B20 cubic lattice structure and weakly doped with Hf (0.5–2 atomic %) in the temperature range from 5 K to 295 K. Two most commonly used nuclei probes, 111In→111Cd and 181Hf → 181 Ta, have been used. The experimental results combined with theoretical density functional calculations indicate that the In/Cd impurities substitute into the Ge-site whereas the Ta/Hf probes substitute into the Rh-site. It has also been found that the Ta/Hf impurity strongly distorts the local crystal environment, whereas the effect from the In/Cd probe is weak. There are no reliable evidences of the magnetic order in the studied alloys at low temperatures.

We have studied the C14 hexagonal Laves phase of YbAg$_2$ at normal conditions and under external pressure up to 19 GPa by the time-differential perturbed angular $\gamma-\gamma$ correlation spectroscopy (TDPAC) using $^{111}$Cd probe nuclei. Under pressure the valence of Yb undergoes a two stage transition from 2.8 to 3. The two stage scenario is characterized by two distinct quadrupole frequencies of $^{111}$Cd probes in silver sublattice, monotonically increasing with pressure and saturating at 8 and 16 GPa. Our experimental data are compared with the density functional studies of the electron band structure of YbAg$_2$, whose results are used for discussion and interpretation of these experiments. We have found that there are two different electric field gradients at inequivalent silver sites and that $4d$-states of silver participate in metal bonding, allowing for the formation of the hexagonal Laves phase.

A new technology for diamond detection in kimberlite based on the tagged neutron method is proposed. The results of experimental researches on irradiation of kimberlite samples with 14.1-MeV tagged neutrons are discussed. The source of the tagged neutron flux is a portable neutron generator with a built-in 64-pixel silicon alpha-detector with double-sided stripped readout. Characteristic gamma rays resulting from inelastic neutron scattering on nuclei of elements included in the composition of kimberlite are registered by six gamma-detectors based on BGO crystals. The criterion for diamond presence in kimberlite is an increased carbon concentration within a certain volume of the kimberlite sample.

New cubic phases of YbGe2.85, TbGe2.85 and DyGe2.85 crystallized in the AuCu3 structure are synthesized at a pressure of 8 GPa. Using the differential perturbed angular γγ-correlation method (TDPAC) we measure the electric field gradient Vzz (the quadrupole frequency ν Q = eQV ZZ / h ) at 111Cd nuclei probes inserted in Ge vacancy lattice sites for all these compounds. In YbGe2.85 the electric field gradient (EFG) is obtained as a function of pressure (up to 8 GPa) at room temperature and as a function of temperature (down to 4 K) at normal pressure. In TbGe2.85 and DyGe2.85 EFG is measured only as a function of temperature (down to 77 K) at normal pressure. In YbGe2.85 the change of EFG and νQ with pressure indicate a change of Yb valance from 2.46 at normal pressure to 2.89 at 8 GPa. In all compounds EFG and νQ are found to be practically independent of temperature.

The time differential perturbed angular γγ-correlation method (TDPAC) has been used to study the hyperfine quadrupole interaction (HQI) of 111 Cd probe nuclei introduced in the novel cubic phase of UGe2 (the AuCu3 crystal lattice). The HQI parameters have been measured as a function of pressure up to 8 GPa. At normal pressure the TDPAC spectrum is described by a single quadrupole frequency of 101.8 MHz. The quadrupole frequency increases with pressure to 118.4 MHz at 5.5 GPa. At a pressure of 7.0 GPa the TDPAC spectrum becomes complex and can be fit by two characteristic quadrupole frequencies: ν 1Q = 117 MHz and ν 2Q = 147 MHz. The appearance of the second quadrupole frequency of 111 Cd probe nuclei has been ascribed to a signal from 111 Cd probes in U sites, which become effective due to a structural phase transition in UGe 2 .

We use the time-differential perturbed angular correlation technique to study nuclear electric quadupole hyperfine interactions of probe 111Cd nuclei in cerium lattice sites at room temperature under pressures up to 8 GPa. We have found that the well known γ → α phase transition in cerium is not isostructural. In α-Ce, the probe 111Cd nuclei reveal a quadrupole electron charge density component that is absent in γ-Ce. The hidden spacial structure of electronic quadrupoles in α-Ce is triple-q antiferroquadrupolar, as was suggested in [14]. We relate our findings to the current understanding of the γ → α phase transition and also report on nuclear quadrupole interactions in other high-pressure phases of cerium: α″ (C2/m space symmetry) and α′ (α-U structure).

Measurements of reactor antineutrino play an important role in the efforts at the frontier of the modern physics. The DANSS collaboration presents preliminary results of a one year run with a cubic meter solid state detector placed below 3.1 GW industrial light water reactor. The experiment is sensitive to sterile neutrino in the most interesting region of mixing parameter space. 2500 scintillation strips of the sensitive volume of the detector have multilayer passive shielding of copper, lead and borated polyethylene and active muon veto. Detector position below the reactor gives an advantage of overburden about 50 m of water equivalent providing factor of six in cosmic muon suppression and eliminating fast neutrons.The detector is placed on a vertically movable platform which allows to change the distance to the reactor core center in the range 10.7-12.7 m within a few minutes. The strips are read out individually by SiPMs and in groups of 50 by PMTs. 5000 inverse beta-decay events per day are collected in the fiducial volume, which is 78% of the whole detector, at the position closest to the reactor. Overburden, active veto and good segmentation of the detector result in an excellent signal to background ratio. The talk is dedicated to the data analysis and preliminary results. The experiment status is also presented.

Search for the β+β+, β+ EC, and EC/EC modes of the 106Cd decay was carried out with the TGV-2 (Telescope Germanium Vertical) low-background multidetector spectrometer installed at the Modane underground laboratory (4800 m w.e.). The measured foil samples ∼50 μm thick and 52 mm in diameter were placed between the entrance windows of the neighboring detectors inside the cryostat. The total measurement time for 10 g of 106Cd enriched to 75% was 8687 h. New limits (at the 90% confidence level, CL) were obtained for the 106Cd half-lives against various branches of the decay to the ground state 0+ and excited states 2+ of the 106Pd daughter nucleus. They are T 1/2(2νβ+β+) ≥ 6.0 × 1019 y, and T 1/2(2νβ+ EC) ≥ 5.9 × 1019 y, and T 1/2(2νEC/EC) ≥ 3.0 × 1020 y for the transitions to the 0+ ground state of 106Pd; T 1/2(2νβ+β+) ≥ 5.7 × 1019 y, T 1/2(2νβ+ EC) ≥ 5.9 × 1019 y, and T 1/2(2νEC/EC) ≥ 4.2 × 1019 y for the transitions to the 2+, 512-keV excited state of 106Pd; and T 1/2(2νEC/EC) ≥ 3.1 × 1019 y for the transition to the 0 1 + , 1334-keV excited state of 106Pd.

The electric quadrupole interaction parameters for impurity 111Cd nuclei in intermetallic RAl3 compounds (R = La, Ce, Sm, Gd, Tb, Dy, Ho, Er, Yb, or Lu) synthesized under high (8 GPa) pressure at high (1800–1900°C) temperatures have been measured using the method of perturbed angular γγ correlations. It has been established by X-ray diffraction analysis that with an increase in the atomic number of the R element the obtained high-pressure phases are crystallized successively in the orthorhombic, hexagonal, and cubic structures. In the compounds with R = La, Ce, Sm, and Gd, deviation from the known structural types and formation of new ones due to the change in the stoichiometric composition have been observed. The data obtained by the method of perturbed angular γγ correlations have confirmed deviation from the specified stoichiometric composition 1R: 3Al for the LaAl3, CeAl3, SmAl3, and GdAl3 compounds and verified the correctness of the stoichiometric composition and the presence of the Cu3Au structural type for the remaining RAl3 high-pressure phases.

The time-differential perturbed angular correlations technique (TDPAC) has been employed for measuring the parameters of hyperfine interactions in earlier known RAl 3 compounds, synthesized at high pressure (8 GPa) and high temperature, where R = La, Ce, Sm, Gd, Tb, Dy, Ho, Er, Yb and Lu. The 111 Cd( 111 In) radioactive atom was used as a probe nucleus. The X-ray method has revealed that with the increase in the atomic number of a rare-earth element R, the obtained RAl 3 high-pressure phases crystallize, respectively, into orthorhombic, hexagonal and cubic structures. It has been found that in the compounds containing R=La, Ce, Sm and Gd, a deviation from earlier known structural types and the formation of new ones is observed, which is associated with the change of the stoichiometric composition of the said compounds. The results of the PAC measurements have confirmed the deviation from the predetermined stoichiometric composition 1R:3Al for the compounds LaAl 3 , CeAl 3 , SmAl 3 and GdAl 3 and have verified the RAl 3 stoichiometric structure for the other high-pressure phases obtained in this work.

Temperature dependencies of the electrical resistivity, magnetic susceptibility, and heat capacity have been obtained in the cubic phase of ${\mathrm{TbGe}}_{2.85}$ (the ${\mathrm{AuCu}}_{3}$ structure), synthesized at high pressure. The macroscopic measurements indicate that a charge density wave is formed below 145 K and an antiferromagnetic ordering is realized below 19 K. Hyperfine interaction data obtained with the time differential perturbed angular correlation method with $^{111}\mathrm{Cd}$ probes inserted in the ${\mathrm{TbGe}}_{2.85}$ lattice suggest that the charge density wave is incommensurate in the temperature region 19--145 K, but becomes commensurate below 19 K. The neutron diffraction reveals a complex antiferromagnetic spiral structure in the magnetically ordered phase. We discuss relations between the charge density wave and helical ordering in ${\mathrm{TbGe}}_{2.85}$ and ${\mathrm{TbPd}}_{3}$.

International audience; A new experimental run of searching for double beta decay of (106)Cd was performed at the Modane underground laboratory (LSM, France, 4800 m w.e.) using the TGV-2 spectrometer, consisting of 32 planar type HPGe detectors with a total sensitive volume of ~400 cm(3). 16 foils of (106)Cd with an enrichment of 99.57% and a total mass of ~ 23.2 g were inserted between the entrance windows of face-to-face detectors. The limit on 2vEC/EC decay of (106)Cd - T(1/2) > 3.7 × 10(20) y at 90% C.F was obtained from the preliminary calculation of experimental data accumulated for 8198 h of measurement. The limits on the resonance OvEC/EC decay of (106)Cd were obtained from the measurement of ~23.2 g of (106)Cd with the low-background HPGe spectrometer Obelix lasted 395 h -T(1/2) (KF, 2741 keV) > 0.9 × 10(20) y and T(1/2) (KK, 2718 keV) > 1.4 × 10(20) y at 90% C.L.

International audience; A new experiment devoted to searches for double electron capture in Cd-106 decay is being performed at the Modane underground laboratory (4800 mwe) with the 32-detector TGV-2 spectrometer. The limit T (1/2)(2 nu EC/EC) > 2.0x10(20) yr at a 90%confidence level (C.L.) was obtained from a preliminary analysis of data obtained over 2250 h of measurements with about 23.2 g sample enriched in the isotope Cd-106 to 99.57%. The limits T (1/2)(KL, 2741 keV) > 0.9 x 10(20) yr and T (1/2)(KK, 2718 keV) a parts per thousand << 1.4 x 10(20) yr at a 90% C.L. on the neutrinoless decay of Cd-106 were obtained from measurements performed with the Obelix low-background spectrometer from high-purity germanium (HPGe spectrometer) for a sample of mass about 23.2 g enriched in the isotope Cd-106.

Time differential perturbed angular gamma-gamma-correlation (TDPAC) method on 111Cd nuclei probes inserted in ZrZn1.9 is used to measure the magnetic hyperfine fields (MHF) at Zr and Zn sites and the electric field gradient (EFG) Vzz at Zn sites as a function of temperature at various pressures and as a function of pressure at the temperature 4 K. Our data indicate that the local magnetic moment of Zr in the magnetically ordered state is substantially larger than its value obtained from the macroscopic measurements and that there is also an induced magnetic moment at the Zn site. We conclude that ZrZn2 is not a simple ferromagnet and discuss a possible type of its magnetic ordering., 7 pages, 6 figures, submitted for publication

International audience; A new experimental run of searching for EC/EC decay of Cd-106 was performed at the Modane underground laboratory (4800 m w.e.) using the TGV-2 spectrometer and similar to 23.2 g Cd-106 with enrichment of 99.57%. The limit on 2 nu EC/EC decay of Cd-106 -T-1/2(2 nu EC/EC) > 3.1x10(20) y, at 90% C. L was obtained from the preliminary calculation of experimental data accumulated for 7018 h of measurement. The limits on the resonance neutrino-less double electron capture decay of Cd-106 were obtained from the measurement of similar to 23.2 g of Cd-106 with the low-background HPGe spectrometer OBELIX lasted 395 h -T-1/2(KL, 2741 keV) > 0.9x10(20) y and T-1/2(KK, 2718 keV) > 1.4x10(20) y at 90% C.L.

The low-background multi-HPGe spectrometer TGV II installed in the Modane Underground Laboratory (France) is described in detail and the results of the background measurements are reported. The spectrometer is focused on the double beta decay measurements with two isotopes—106Cd ( 2 ν EC / EC mode) and 48Ca ( β β mode). A basic summary of the physics of β β decay (especially EC/EC mode) is also given.

A search for double electron capture of 106Cd was performed at the Modane Underground Laboratory (4800 m w.e.) using a low-background and high-sensitivity multidetector spectrometer TGV-2 (Telescope Germanium Vertical). New limits on β+/EC, EC/EC decays of 106Cd were obtained from preliminary calculations of experimental data accumulated for 4800 h of measurement of 10 g of 106Cd with enrichment of 75%. They are \(T_{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}}^{2\nu \beta ^ + EC} \) > 9.1 × 1018 yr, \(T_{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}}^{2\nu {{EC} \mathord{\left/ {\vphantom {{EC} {EC}}} \right. \kern-\nulldelimiterspace} {EC}}} \) > 1.9 × 1019 yr for transitions to the first 2+, 511.9 keV excited state of 106Pd, and \(T_{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}}^{2\nu \beta ^ + EC} \) > 1.3 × 1019 yr, \(T_{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}}^{2\nu {{EC} \mathord{\left/ {\vphantom {{EC} {EC}}} \right. \kern-\nulldelimiterspace} {EC}}} \) > 6.2 × 1019 yr for transitions to the ground 0+ state of 106Pd. All limits are given at 90% C.L.

A four-detector spectrometer of perturbed angular γγ correlations is developed for investigation of hyperfine interactions in condensed matter. It allows measurements with practically any type of detectors. A unique circuit design involving a specially developed Master PAC unit combined with a computer allows a substantially higher efficiency, reduced set-up time and simpler operation in comparison with traditional PAC spectrometers. A cryostat and a high-temperature oven allow measurements in the temperature range from 120 to 1300 K. An encased electromagnet makes it possible to generate a magnetic field up to 2 T on a sample. The measurement system includes a press with a specially designed high-pressure chamber allowing on-line PAC measurements in samples under pressure up to 60 GPa.

Present status of the experiment TGV II is given. The experiment TGV II is devoted to the measurement of double-beta decay of 106Cd and 48Ca. The new HPGe multi-detector TGV spectrometer has been constructed and installed in the Modane underground laboratory (in France). Preliminary results of the first background measurement are presented.

The TGV (Telescope Germanium Vertical) collaboration is interested in the measurement of double-beta decay of 48Ca (TGV I) and 106Cd (TGV II). The background in the experiment TGV I has been suppressed by several methods. One of them was based on distinguishing between electrons and γ-rays due to the different rise time of the signals obtained from semiconductor detector. Two experimental setups have been tested, the first one used a charge-sensitive analog-to-digital converter, while the second one utilized digital oscilloscope. The reduction of the background counting rate (due to γ-rays) in single HPGe detector by a factor of (1.4-3.8) was reached.

The DANSS project is aimed at creating a relatively compact neutrino spectrometer which does not contain any flammable or other dangerous liquids and may therefore be located very close to the core of an industrial power reactor. As a result, it is expected that high neutrino flux would provide about 15,000 IBD interactions per day in the detector with a sensitive volume of 1 m3. High segmentation of the plastic scintillator will allow to suppress a background down to a ~1% level. Numerous tests performed with a simplified pilot prototype DANSSino under a 3 GWth reactor of the Kalinin NPP have demonstrated operability of the chosen design. The DANSS detector surrounded with a composite shield is movable by means of a special lifting gear, varying the distance to the reactor core in a range from 10 m to 12 m. Due to this feature, it could be used not only for the reactor monitoring, but also for fundamental research including short-range neutrino oscillations to the sterile state. Supposing one-year measurement, the sensitivity to the oscillation parameters is expected to reach a level of sin2(2θnew) ~ 5 × 10−3 with Δ m2 ⊂ (0.02–5.0) eV2.

We describe an improved follow-up of our previous spin-neutrino correlation experiment, where the 1229 and 2171 keV gamma-rays emitted after the 28 Si( μ , ν ) 28 Al(1 + , 2202 keV) reaction were observed by high-resolution HPGe detectors at different angles with respect to the muon spin. In the experiment described here, a magnetic field was used both to select events according to the spin-gamma angle and to measure the residual muon polarization by the muSR method. We further increase the precision of our result making use of new experimental and theoretical information. We obtain for the parameter x ≡ M (2)/ M (−1) the value of x =0.239±0.029, which can be compared to our previous result (Brudanin et al., Nucl. Phys. A 587 (1995) 577) x =0.254±0.034 and to the value x =0.315±0.080 obtained recently at TRIUMF with a different technique. The coupling-constant ratio g P / g A was deduced from the mean value x =0.247±0.027. Using renormalized transition operators calculated recently, we obtained for g P / g A the solution range of −1.0 to +1.3 to be compared to the value of 7 predicted by PCAC for the free nucleon. This result confirms the strong quenching of g P / g A reported earlier.

Present status of experiments TGV I and TGV II is given. The TGV I collaboration has studied the double-beta decay of 48Ca with a low-background and high sensitivity Ge multi-detector spectrometer TGV (Telescope Germanium Vertical). The preliminary results of $${\text{T}}_{{\text{1/2}}}^{{\text{2}}\nu \beta \beta } = (4.2_{ - 1.3}^{ + 3.3} ) \times 10^{19} $$ years and $${\text{T}}_{{\text{1/2}}}^{0\nu \beta \beta } >1.5 \times 10^{21} $$ years (90% CL) for double-beta decay of 48 Ca has been found after the processing of experimental data obtained after 8700 hours of measuring time using approximately 1 gramme of 48Ca. The aim of the experiment TGV II is the development of the experimental methods, construction of spectrometers and measurement of the ββ decay (β+β+, β+/EC, EC/EC) of 106Cd particularly the 2νEC/EC mode. The theoretical description and performance of the TGV II spectrometer are also given.

Using time-differential perturbed angular correlation spectroscopy we have measured the electric field gradient (EFG) at $^{111}\text{C}\text{d}$ probe nuclei in solid Ce in a pressure range up to 8 GPa. Covering various allotropic phases of Ce, we find that the value of the EFG in the cubic $\ensuremath{\alpha}$ phase is almost four times larger than in the cubic $\ensuremath{\gamma}$ phase and close to values in the noncubic phases ${\ensuremath{\alpha}}^{\ensuremath{'}}$ and ${\ensuremath{\alpha}}^{\ensuremath{''}}$. These results together with the differences in time modulation of the spectra are interpreted as evidence for quadrupolar electronic charge-density ordering and symmetry lowering at the $\ensuremath{\gamma}\ensuremath{\rightarrow}\ensuremath{\alpha}$ transition while the lattice remains face-centered cubic.

The quadrupole interaction at $^{111}\mathrm{Cd}$ impurity nuclei in the intermediate-valence compound $\mathrm{Yb}{\mathrm{Al}}_{2}$ has been measured under pressure up to $80\phantom{\rule{0.3em}{0ex}}\mathrm{kbar}$ by the time-differential perturbed angular correlation spectroscopy. It was found that the quadrupole frequency ${\ensuremath{\nu}}_{Q}$ measured on the $^{111}\mathrm{Cd}$ nuclei located at the Al sites in $\mathrm{Yb}{\mathrm{Al}}_{2}$ varies nonlinearly and increases by almost four times with the pressure increase up to $80\phantom{\rule{0.3em}{0ex}}\mathrm{kbar}$. A linear correlation between the mean Yb valence, derived from Yb ${L}_{3}$ OFY-XAS and RXES measurements, and the electric field gradient (the quadrupole frequency ${\ensuremath{\nu}}_{Q}=eQ{V}_{zz}∕h$) has been observed. The quadrupole frequencies on $^{111}\mathrm{Cd}$ in the $\mathrm{Gd}{\mathrm{Al}}_{2}$, $\mathrm{Yb}{\mathrm{Al}}_{3}$, $\mathrm{Tm}{\mathrm{Al}}_{3}$, and $\mathrm{Ca}{\mathrm{Al}}_{2}$ compounds have been also measured. The possibility of determining the valence of Yb in the Yb compounds with $p$ metals from the relation ${\ensuremath{\nu}}_{Q}\mathbf{(}\ensuremath{\upsilon}(P)\mathbf{)}={\ensuremath{\nu}}_{2}+({\ensuremath{\nu}}_{3}\ensuremath{-}{\ensuremath{\nu}}_{2})\ensuremath{\upsilon}(P)$ has been considered.

Present status of the experiment TGV II which is devoted to the measurement of double-beta decay of 106Cd is given. The low background spectrometer TGV II is installed in the Modane Underground Laboratory and has been running from February 2005 with approx 10 grams of 106Cd enriched at 75%. After an analysis of 3736 hours of experimental data the new improved half-life limit for 2νEC/EC decay of 106Cd (0 g.s. + → 0 g.s. + ) is given as T 1 2/2 > 4.8 × 1019 years (90% CL). The search for 2νEC/EC decay of 106Cd to the excited states of 106Pd allows to determine the limits of the half-lives T 1 2/2 (0 g.s. + → 2 1 + ) > 3.9 × 1019 years (90% CL) and T 1 2/2 (0 g.s. + → 0 1 + ) > 5.8 × 1019 years (90% CL).

This Letter describes a collaborative TGV (Telescope Germanium Vertical) study of the double beta decay of 48Ca with a low-background and high sensitivity Ge multi-detector spectrometer. The results of T1/22νββ=(4.2+3.3−1.3)×1019 years and T1/20νββ>1.5×1021 years (90% CL) for double beta decay of 48Ca were found after processing experimental data obtained after 8700 hours of measuring time, using approximately 1 gramme of 48Ca. The features of a TGV-2 experiment are also presented.

A high sensitivity double beta spectrometer TGV (Telescope Germanium Vertical) has been developed. It is based on 16 HPGe detectors of volume 1200 × 6 mm3 each in the same cryostat. The TGV spectrometer was proposed for the study of ultrarare nuclear processes (e.g. 2νββ, 0νββ, 2νEC/EC). Details of the TGV spectrometer construction are described, the principles of background suppression, the results of Monte Carlo simulations and the results of test background measurements (in Dubna and Modane underground laboratory) are provided.

The observation with high-resolution Ge detectors of the 1229 and 2171 keV gamma-rays emitted after the 28Si(μ, ν)28Al(1+, 2202 keV) reaction allowed us to determine the nuclear-amplitude ratio x ≡ M(2) M(−1) characteristic of this muon-capture reaction. Using the nuclear-structure dependent evaluation of various correction terms (model of Ciechanowicz), our result x = +0.254±0.034 provides for the induced pseudoscalar coupling gp the ratio g p g a (0.848m μ 2 ) = 3.4 ± 1.0 , to be compared to the PCAC prediction of g p g a = 7 . The model dependence of this apparent quenching remains to be assessed.

The TGV II (Telescope Germanium Vertical) facility is a low background spectrometer operated in Modane Underground Laboratory. It aims at the study of double electron capture of 106Cd. The spectrometer is composed of 32 HPGe planar detectors interleaved with thin-foil samples made of 106Cd enriched to 75%. In 2006, the main run of phase I (1 year duration) was terminated yielding a new limit on half-life for two-neutrino double electron capture in 106Cd as 2.0x1020y. The new limit is significantly higher (by almost three orders of magnitude) than those already published.

A short description of experiment TGV (double beta decay of48Ca) is given. The measurement started in the Modane underground laboratory in August 1996. The first result ofT 1 2/0 ≥ 4.6 × 1020 years [90% CL] after 2545 hours is presented.