Search

In the near future, two radio telescopes will be installed in the Indonesian region. These telescopes are proposed to be integrated into the existing Very Long Baseline Interferometry (VLBI) network both for astronomical and geodetical purposes. Here we simulate the impact of the inclusion of the future Indonesian antennas to the estimates of Earth Orientation Parameters and the station position. The simulation was performed in two types of VLBI sessions. First, we analyse the contribution of Indonesian antennas to the existing intensive session INT3 (IN320-314), which focuses on the estimation of dUT1. We found that the addition of Indonesian antennas has reduced the estimated dUT1 repeatability value by about 25%. Next, we simulate the 24-hour session by considering two existing network configurations, which are R4 (R4934) and AOV (AOV049). Overall we found that the addition of Indonesian antennas to each network configuration decreases the repeatability value of the Earth Orientation Parameter by about 20%. Meanwhile, the repeatability value of station position is reduced up to 12%. This reduction is already achieved even when we include only one Indonesian antenna.

The perturbations to the Milky Way cause the disk to have bending or breathing wave, flare, and warp. Both spatial analyses from stellar and gas show the Milky Way warp can be approached with sinusoidal function to the Galactocentric longitude. In this research, we aim to find evidence of the transient Milky Way warp using kinematics data of the Red Giant Branch (RGB) stars from Gaia Data Release 2. We only use RGB stars with positive parallaxes and small parallax uncertainties where ϖ > 0 and ϖ/σϖ > 5, respectively. Using the linear warp model, we find the Milky Way warp starts on Rw = 10.72 kpc, with the amplitude (γw ) of 0.39 and the Line of Node lies on ϕw = −5.26°. Assumed the warp is a static long-lived feature on kinematics distribution, where all of the warp parameters are constant by the time, the observed vertical velocity (Vz ) is less than the expected one. The maximum Vz is not exceeded to 12.5 km/s rather 20 km/s derived from the proposed model. It infers that the warp drive on the Milky Way is a transient feature. One of the possible reasons is the recent interaction with satellite galaxies in perturbing the outer disk of the Milky Way.

Dark matter is usually considered responsible for the flat rotation curves observed at the outer radii of spiral galaxies. Since the existence of dark matter has not been indisputably detected by experiments, magnetic field is sometimes proposed to be substitute for dark matter in explaining the shape of rotation curves of spiral galaxies. Magnetic field that interacts with cosmic rays generate pressure, which in turn accelerates gas flow/dynamics and affects the speed of gas rotation. Some other studies discuss the possibilities that the flat or even increased rotation curves at the outer radii may be attributed both to dark matter and the galactic magnetic fields. In this work, we examined 16 rotation curve data of dwarf spiral galaxies in the Spitzer Photometry and Accurate Rotation Curves (SPARC) catalog obtained by Spitzer in 3.6 µm. We find that the shape of the rotation curves of the dwarf spiral galaxies cannot be explained by the contribution of magnetic field alone, due to stability issues. However, adding some contribution of magnetic field to the dark matter component explains the rotation curves at the large radii better, compared to dark matter without magnetic field. We therefore determined the maximum contribution of the magnetic field for the 16 dwarf spiral galaxies.

In this paper, we reconstruct matter power spectrum of a cosmological model in which coupled scalar field acts as dark energy. The coupled scalar field (CSF) dark energy we propose here is a generalized model of quintessence, k-essence or phantom coupled to dark matter (non-baryonic matter) via a coupling constant. The existence of coupling between dark energy and matter allows energy to transfer between them, which may give rise to different observational signatures, especially at perturbation level, including matter power spectrum. In this work, through analytical exploration we studied that possible signature in matter power spectrum that maybe induced by this mode.

Fragmentation and fission of giant molecular clouds occasionally results in a pair of gravitationally bound star clusters that orbit their mutual centre of mass for some time, under the influence of internal and external perturbations. We investigate the evolution of binary star clusters with different orbital configurations, with a particular focus on the Galactic tidal field. We carry out $N$-body simulations of evolving binary star clusters and compare our results with estimates from our semi-analytic model. The latter accounts for mass loss due to stellar evolution and two-body relaxation, and for evolution due to external tides. Using the semi-analytic model we predict the long-term evolution for a wide range of initial conditions. It accurately describes the global evolution of such systems, until the moment when a cluster merger is imminent. $N$-body simulations are used to test our semi-analytic model and also to study additional features of evolving binary clusters, such as the kinematics of stars, global cluster rotation, evaporation rates, and the cluster merger process. We find that the initial orientation of a binary star cluster with respect to the Galactic field, and also the initial orbital phase, are crucial for its fate. Depending on these properties, the binaries may experience orbital reversal, spiral-in, or vertical oscillation about the Galactic plane before they actually merge at $t\approx100$~Myr, and produce rotating star clusters with slightly higher evaporation rates. The merger process of a binary cluster induces an outburst that ejects $\sim10\%$ of the stellar members into the Galactic field., 14 pages, 7 figures, accepted for publication in MNRAS

We studied a cluster family in the northern part of the Carina Nebula (NGC 3372) a group of clusters near NGC 3324 (Tr 15, NGC 3293, Loden 165, Loden 153 and IC 2581). We used data from UCAC4 to determine the cluster"s membership and the near infrared CMDs of each cluster. We analyzed the spatial density and elongation as a function of radius for each cluster and found a possible interaction between NGC 3293 and Loden153. However, the shape distortion of NGC 3324 cannot be evaluated because of the inhomogenity in the coverage of UCAC4 in the east part of NGC 3324.

Local dark matter density, ρdm, is one of the crucial astrophysical inputs for the estimation of detection rates in dark matter direct search experi- ments. Knowing the value also helps us to investigate the shape of the Galactic dark halo, which is of importance for indirect dark matter searches, as well as for various studies in astrophysics and cosmology. In this work, we performed kinematics study of stars in the solar neighborhood to determine the local dark matter density. As tracers we used 95,543 K-dwarfs from Gaia DR2 inside a heliocentric cylinder with a radius of 150 pc and height 200 pc above and below the Galactic mid plane. Their positions and motions were analyzed, assum- ing that the Galaxy is axisymmetric and the tracers are in dynamical equilib- rium. We applied Jeans and Poisson equations to relate the observed quantities, i.e. vertical position and velocity, with the local dark matter density. The tilt term in the Jeans equation is considered to be small and is therefore neglected. Galactic disk is modelled to consist of a single exponential stellar disk, a thin gas layer, and dark matter whose density is constant within the volume consid- ered. Marginalization for the free parameters was performed with Bayesian theorem using Markov Chain Monte Carlo (MCMC) method. We find that ρdm= 0.0116 ± 0.0012 MO/pc or ρdm= 0.439 ± 0.046 GeV/cm3, in agreement within the range of uncertainty with results of several previous studies.

Ultraluminous X-ray sources (ULXs) are known as extragalactic point-like X-ray sources with luminosities considerably in excess of the maximum luminosity of a 10 solar mass accreting black hole. X-ray spectra of ULXs have been investigated in many previous studies. However, sparse observations render it more difficult to convincingly distinguish between two competing scenarios, i.e. sub-critical accreting intermediate-mass black hole and super-critical accreting stellar remnant black hole. Here, we report our investigation of a sample of nearby ULXs, as well as their host galaxies, in order to get a more complete understanding of their nature. Multiwavelength analysis was applied to study these ULXs. From X-ray study, we found that most ULXs in our sample do exhibit spectral variability in which higher energy X-ray predominates the spectra as the source becomes brighter. We also compiled some properties of the host galaxies, as a proxy of ULX environment. We found that ULXs in our sample can neither be exclusively associated with a certain type of morphology, nor with high nuclear activity. We also found that 12 out of 19 ULXs reside in host galaxies with star formation rate of less than 1 solar mass per year.

A universe containing a coupled scalar field would have different dynamical evolution compared to uncoupled cases. Significant differences are expected to emerge during matter dominated era, where scalar field density mimics how matter density evolves, by becoming subdominant. Analysis of the dynamics was investigated both analytically and numerically through phase plane method, and we obtained two attractor solutions which are compatible to a late time cosmic acceleration as the ending of matter dominated era. Ordinary scalar field triggers an acceleration with stable attractor solution which converges to ωϕ = ωeff ≈ −1. Whereas, phantom scalar field allows negative values for its own energy (ωeff ˂ −1 and Ωϕ ˂ 0); however this is not stable, therefore it will be caught by attractor solution which is stable to ωϕ = ωeff ≈ −1. In addition, we found cosmological parameters generated from both analytical and numerical calculations, i.e. ωϕ , Ωϕ and ωeff , by assuming a flat universe. The existence of a coupling constant Q between scalar field and matter induces different structure growth compared to uncoupled cases and standard cold dark matter (CDM) model. During matter dominated era, ordinary scalar field induces growth of structures so that it becomes faster than the standard model does, whereas phantom scalar field slows down the growth of structures. During scalar field dominated era (far in the future), we obtained that formed structures or density contrasts will decay in a similar way as in uncoupled cases, whereas following phantom scenario, the decay of formed structures occurs faster and more significant. This result is associated to background dynamics which shows that big rip will be the relevant fate of our universe.

Discrepancies between expected and observed rotation curves in spiral galaxies are commonly interpreted as evidence for the existence of dark matter. Dark matter can explain the observed flat rotation curves at the outer radii. However, some rotation curves of spiral galaxies exhibit rising features at large distances from the galactic centers that cannot be attributed to dark matter alone. Addition of magnetic field contribution to the rotation curves of spiral galaxies has been proposed in some literature to explain the rising features. In this work we investigated the rotation curves of three spiral galaxies, i.e. NGC 2841, NGC 6946, and M 31, whose profiles of azimuthal magnetic field are available in literature. In general, decomposition scenarios using four components (stellar disk, gas, bulge, and dark matter halo) with magnetic field fit better to the observational data.

In the standard model neutrinos consist of three species (flavors) and are massless. However, solar neutrino problem that was solved by neutrino oscillations requires that neutrinos have non-zero masses. Another support for non-zero neutrino masses comes from kinematic experiments. Oscillation experiments give rise to a further problem regarding the order of neutrino masses, known as the neutrino mass hierarchy problem, i.e. whether the hierarchy is normal or inverted. On cosmological scales, massive neutrinos affect Cosmic Microwave Background (CMB) and Large Scale Structure (LSS) formation. The impact of massive neutrinos is imprinted in the power spectrum of CMB, and in the LSS matter power spectrum as well. Since neutrinos affect events in the universe, it is possible to constrain neutrino properties based on cosmological observations. This work is aiming at constraining neutrino total mass from cosmological observations in the two hierarchy scenarios, i.e. normal and inverted hierarchies, and also at determining which neutrino mass hierarchy is favoured by cosmological observations. To constrain neutrino total mass we employed CosmoMC and performed Bayesian analysis with MCMC algorithm, while neutrino mass hierarchy was determined based on Bayes factors, in which likelihoods of the two hierarchy scenarios were compared. In addition, neutrino individual masses were estimated by combining results of oscillation experiments. Depending on the dataset used, different total mass constraints were obtained. The tightest constraint comes from a combination of CMB + LSS + BAO + Supernova data, i.e. Σmv < 0.183 eV (normal hierarchy) and Σmv < 0.188 eV (inverted hierarchy) with 95% C.L. The Bayes factors analysis prefers normal hierarchy, although with weak evidence.

We report the first measurements of radio frequency spectrum occupancy performed at sites aimed to host the future radio astronomy observatory in Indonesia. The survey is intended to obtain the radio frequency interference (RFI) environment in a spectral range from low frequency 10 MHz up to 8 GHz. The measurements permit the identification of the spectral occupancy over those selected sites in reference to the allocated radio spectrum in Indonesia. The sites are in close proximity to Australia, the future host of Square Kilometre Array (SKA) at low frequency. Therefore, the survey was deliberately made to approximately adhere the SKA protocol for RFI measurements, but with lower sensitivity. The RFI environment at Bosscha Observatory in Lembang was also measured for comparison. Within the sensitivity limit of the measurement equipment, it is found that a location called Fatumonas in the surrounding of Mount Timau in West Timor has very low level of RFI, with a total spectrum occupancy in this measured frequency range being about 1 %, mostly found at low frequency below 20 MHz. More detailed measurements as well as a strategy for a radio quiet zone must be implemented in the near future.

Big bang theory states that universe emerged from singularity with very high temperature and density, then expands homogeneously and isotropically. This theory gives rise standard cosmological principle which declares that universe is homogeneous and isotropic on large scales. However, universe is not perfectly homogeneous and isotropic on small scales. There exist structures starting from clusters, galaxies even to stars and planetary system scales. Cosmological perturbation theory is a fundamental theory that explains the origin of structures. According to this theory, the structures can be regarded as small perturbations in the early universe, which evolves as the universe expands. In addition to the problem of inhomogeneities of the universe, observations of supernovae Ia suggest that our universe is being accelerated. Various models of dark energy have been proposed to explain cosmic acceleration, one of them is cosmological constant. Because of several problems arise from cosmological constant, the ...

We present first significant limits on WIMP dark matter by the phonon-light technique, where combined phonon and light signals from a scintillating cryogenic detector are used to suppress the non-nuclear recoil background. The performance of the detectors developed for the second phase of the CRESST experiment will be discussed and data collected with two prototype modules in a short run, corresponding to a net exposure of 20.5 kg days, will be presented. (c) 2005 Elsevier B.V. All rights reserved.

Results of the CRESST experiment at Gran Sasso using 262-g sapphire calorimeters with tungsten phase transition thermometers are presented. Calibration and analysis methods are described. Data taken in 2000 have been used to place limits on WIMP dark matter particles in the Galactic halo. The sapphire defectors are especially sensitive to low-mass WIMPs with spin-dependent interaction and improve on existing limits in this region. (C) 2003 MAIK "Nauka/Interperiodica".

Large Magellanic Cloud (LMC) has been known to host a significant fraction of binary star clusters whose dynamical and physical nature become interesting issue in accordance with the history of the galaxy. To understand the characteristics and the history of the binary clusters, it is important to establish a well-sampled statistics of this population. Among ~ 3100 star clusters (excluding associations), there are 634 clusters considered as binary/multiple cluster candidates. In this paper, the empirical statistics of the population, including spatial, size, separation, and age distribution are constructed using updated data. The current cluster compilation includes the ages of 88% group components, which is three times more complete compared to the previous study. From the established statistics, we found an evidence that cloud fissions become the most probable mechanism of binary star cluster formation. Size and separation distribution of the clusters in binary/multiple systems show the importance of dynamical interaction within the systems.

The CRESST Phase II experiment at Gran Sasso is using 300 g scintillating CaWO4 crystals as absorbers for direct WIMP (weakly interactive massive particles) detection. The phonon signal in the CaWO4 crystal is registered in coincidence with the light signal, which is measured with a separate cryogenic light detector. The absorber crystal and the silicon light detector are read out by tungsten superconducting phase transition thermometers (W-SPTs). As a result an active discrimination of the electron recoils against nuclear recoils is achieved. Results on the properties of the detector modules and on the WIMP sensitivity are presented. (C) 2005 Published by Elsevier B.V.

We present first significant limits on WIMP dark matter by the phonon-light technique, where combined phonon and light signals from a scintillating cryogenic detector are used. Data from early 2004 with two 300 g CRESST-II prototype detector modules are presented, with a net exposure of 20.5 kg days. The modules consist of a CaWO4 scintillating ``target'' crystal and a smaller cryogenic light detector. The combination of phonon and light signals leads to a strong suppression of non-nuclear recoil backgrounds. Using this information to define an acceptance region for nuclear recoils we have 16 events from the two modules, corresponding to a rate for nuclear recoils between 12 and 40 keV of (0.87 +- 0.22) events/(kg day). This is compatible with the rate expected from neutron background, and most of these events lie in the region of the phonon-light plane anticipated for neutron-induced recoils. A particularly strong limit for WIMPs with coherent scattering results from selecting a region of the phonon-light plane corresponding to tungsten recoils, where the best module shows zero events., Comment: 24 pages, 10 figures, version v2 includes figures with improved print quality, v3 accepted for publication in astroparticle physics

With simultaneous measurement of the temperature signal and the scintillation light of a CaWO4 absorber crystal, it is possible to reject the gamma and electron background in the Cryogenic Rare Event Search with Superconducting Thermometers experiment. In order to understand the different events from various particles correctly a neutron calibration experiment and other tests are necessary. Using an existing accelerator facility these tests will be performed above ground. For such an experiment, a detector with good stability at high count rates is necessary. The detectors used in the Gran Sasso Laboratory are equipped with W-thermometers. They show long decay times and need active stabilisation and therefore are not well suitable for experiments with high count rates. We report on developments and first results on detectors based on Ir/Au-thermometers in electrothermal feedback mode.

We investigated the cause of somewhat bimodal distribution of the Near-Earth Asteroids (NEAs) inclination. Numerical integrations, in term of Newtonian gravitation including thermal effect, were carried out on 270 artificial objects for 400 thousand years and on a thousand random-selected NEAs for one million years. Orbital coupling between distributions of semi major axis (a) and inclination (i) segregated at about 2 AU turns out to exhibit bump at about inclination of about 20°. This bump is emerged because of the diversity in orbital mobility of NEAs between regions of a 2 AU, in which correspond to the secular and the mean-motion resonances. NEAs which located at a > 2 AU are dominated by the asteroids whose i < 15° and are protected by the secular resonance (υ6) of Saturn. In addition, thermal effect play a role in delivering NEAs through perihelia of the Terrestrial planets, mainly affect orbital diffusion of NEAs when passing through the υ6 region, and somehow restrain NEAs from fall...

A triple star system consists of a closer (inner) binary and another farther (outer) component orbiting the closer binary. The stability of such triple star systems has been of interest to many authors. In one of the studies, it is found that the instability of triple stars system is also determined by its critical period ratio (outer/inner), beside its mass ratio. In this study, they considered stars of mass 0.01 – 100 solar mass, with mass ratio range of 1 – 100. By using Mercury code, we extend their work to study the effects of initial inclination to the stability of the systems. The code validation results in an agreement with their results, i.e the bigger the period ratio of a system from its critical period ratio, the system will tend to be more stable. In this paper, we report the results of our simulations which have been performed to see how initial inclination affects the stability of a system. A grid of three initial parameters (distance, inclination, and phase) has been used to initiate the simulations. We conclude that the bigger the outer binary’s inclination, the system will be more stable.

In a region of very high dark matter density such as near the Galactic center, stars may capture a large amount of dark matter. The existence of dark matter in the core of a star may trigger annihilation processes which provide additional source of energy for the star while significantly alters stellar interior and evolution. We employed DarkStars code to simulate the evolution of main sequence stars under the influence of dark matter. Simulations show that energy injection by dark matter annihilation to stars causes decreasing in temperature and pressure in the stellar core. Hence, the rate of hydrogen burning drops. Stars are able to maintain hydrogen in their core for longer period and extend their lifetime in the main sequence. Lower mass stars are influenced more significantly by dark matter than higher mass stars.

In the CRESST-II experiment, scintillating CaWO4 crystals are used as absorbers for direct weakly interacting massive particles (WIMP) detection. Nuclear recoils can be discriminated against electron recoils by measuring phonons and scintillation light simultaneously. The absorber crystal and the silicon light detector are read out by tungsten superconducting phase transition thermometers. Results on the sensitivity of the phonon and the light channel, radiopurity, the scintillation properties of CaWO4, and on the WIMP sensitivity are presented. (C) 2003 Elsevier B.V. All rights reserved.

Binarity among stellar clusters in galaxy is such a reality which has been realized for a long time, but still hides several questions and problems to be solved. Some of binary star clusters are formed by close encounter, but the others are formed together from similar womb. Some of them undergo separation process, while the others are in the middle of merger toward common future. The products of merger binary star cluster have typical characteristics which differ from solo clusters, especially in their spatial distribution and their stellar members kinematics. On the other hand, these merger products still have to face dissolving processes triggered by both internal and external factors. In this study, we performed N-body simulations of merger binary clusters with different initial conditions. After merging, these clusters dissolve with greater mass-loss rate because of their angular momentum. These rotating clusters also experience more deceleration caused by external tidal field., presented in International Conference on Mathematics and Natural Sciences 2012

Since 1950s, several authors have reported the so-called anomalous gravity during the total solar eclipses through various experiments. To address this issue, in the moment of the total solar eclipse of 9 March 2016 passing most regions in Indonesia, we undertook microgravity measurements using two precise gravimeters. The measurements were made at two locations: (1) Poso (central Sulawesi), a location close to the centre passage of the total eclipse and (2) Lembang (West Java), the site of Bosscha Observatory, where the partial solar eclipse occurred. The two sites are selected to measure the possible different influence of the eclipse on aligning the three objects. The measurements were recorded three days before and one day after the eclipse at various intervals from 30 seconds to a short time at 5 seconds. The finer recording was performed several hours before and after the total eclipse. This measurement allowed detailed analysis, not only in time but also in frequency range. A detailed analysis is presented in this paper. We consider all possible geophysical as well as atmospheric effects. The residual data show that the shielding effect, usually thought as responsible factor on anomalous gravity, is not significant.

Ultraluminous X-ray sources (ULXs) are defined as non-nuclear point-source objects with apparent X-ray luminosities, Lx > 2×1039 erg s-1, in the 0.3-8 keV band. ULXs are often explained using two different scenarios, (1) ULXs as intermediate mass black hole (IMBH) with sub-Eddington accretion and (2) ULXs as stellar mass black hole with super-Eddington accretion. There are two methods that commonly used to study the characteristics of ULXs. One method is to study the X-ray spectra of ULXs, to determine the characteristics of their accretion flows from fitting their spectra using available spectral models. The other method is to investigate how population of ULXs correlate with their environment, in this case their host galaxies. Our goal is to find correlation between ULXs and the properties of its host galaxies, for example with Star Formation Rate (SFR), mass and morphology. From this study we found a positive correlation between ULXs number and SFR. From X-ray luminosity function, we found upper limit of black holes mass that power ULXs is about 100 M⊙.

The aim of this research is to detect misconceptions in the concept of physics at high school level by using astronomy questions as a testing instrument. Misconception is defined as a thought or an idea that is different from what has been agreed by experts who are reliable in the field, and it is believed to interfere with the acquisition of new understanding and integration of new knowledge or skills. While lack of concept or knowledge can be corrected with the next instruction and learning, students who have misconceptions have to "unlearn" their misconception before learning a correct one. Therefore, the ability to differentiate between these two things becomes crucial. CRI is one of the methods that can identify efficiently, between misconceptions and lack of knowledge that occur in the students. This research used quantitative- descriptive method with ex-post-facto research approach. An instrument used for the test is astronomy questions that require an understanding of physics concepts to solve the problem. By using astronomy questions, it is expected to raise a better understanding such that a concept can be viewed from various fields of science. Based on test results, misconceptions are found on several topics of physics. This test also revealed that student's ability to analyse a problem is still quite low.

We present results on WIMP dark matter interaction, obtained using cryogenic phonon-scintillation detectors. The targets are CaWO4 scintillating crystals with phonon sensors, while scintillation is detected with an associated cryogenic light detector. The combination of phonon and light signals leads to a strong suppression of nonnuclear recoil backgrounds. Results obtained before the upgrade of CRESST are presented and a status report on the upgrade itself is given.

The CRESST experiment is looking for non-baryonic particle dark matter via nuclear scattering in CaWO4. The simultaneous measurement of the heat and the scintillation light generated by an event in a CaWO4 single crystal is used to discriminate between electron and nuclear recoils thanks to their different light output. This allows an efficient suppression of the electron recoil background. The set-up consists of modules with a 300 g CaWO4 crystal mounted in a reflective housing together with a light detector. The heat signal is read out using a superconducting transition-edge sensor (TES) made of tungsten evaporated directly on to the crystal that is operated at a few mK. Currently the second phase of the experiment is being set up at the Laboratori Nazionali del Gran Sasso in which it is planned to run 33 detector modules providing a total target mass of 10 kg. First test runs with prototype detectors have been successfully performed.

For the first time the natural alpha decay of W-180 has been unambiguously detected in a (gamma, beta and neutron)-free background spectrum. This has been obtained by simultaneously measuring phonon and light signals with CRESST 11 cryogenic detectors. Results on the radio purity of the detectors and on the measured half-life of W-180 are presented.

The natural $\ensuremath{\alpha}$-decay of $^{180}\mathrm{W}$ has been unambiguously detected for the first time. The $\ensuremath{\alpha}$ peak is found in a ($\ensuremath{\gamma}$, $\ensuremath{\beta}$, and neutron)-free background spectrum. This has been achieved by the simultaneous measurement of phonon and light signals with the CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) cryogenic detectors. A half-life of ${T}_{1∕2}=(1.8\ifmmode\pm\else\textpm\fi{}0.2)\ifmmode\times\else\texttimes\fi{}{10}^{18}\phantom{\rule{0.3em}{0ex}}\text{years}$ and an energy release of $Q=[2516.4\ifmmode\pm\else\textpm\fi{}1.1(\mathrm{stat.})\ifmmode\pm\else\textpm\fi{}1.2(\mathrm{sys.})]\phantom{\rule{0.3em}{0ex}}\mathrm{keV}$ have been measured. New limits are also set on the half-lives of the other naturally occurring tungsten isotopes.

The neutron flux induced by radioactivity at the Gran Sasso underground laboratory is revisited. We have performed calculations and Monte Carlo simulations; the results offer an independent check to the available experimental data reported by different authors, which vary rather widely. This study gives detailed information on the expected spectrum and on the variability of the neutron flux due to possible variations of the water content of the environment., Comment: 14 pages, 3 figures, systematic uncertainties added

Results of the CRESST experiment at Gran Sasso using 262 g sapphire calorimeters with tungsten phase transition thermometers are presented. Calibration and analysis methods are described. Data taken in 2000 have been used to place limits on WIMP dark matter particles in the galactic halo. The sapphire detectors are especially sensitive for low-mass WIMPS with spin-dependent interaction and improve on existing limits in this region.

The neutrino capture reaction 71Ga(νe,e−)71Ge and the reverse EC-decay is used by GNO to monitor the flux of solar neutrinos in a routinely operating neutrino observatory. Low temperature detectors (LTDs) offer a better performance concerning efficiency, energy resolution and threshold than the proportional counters that are used now. We report on measurements with a detector setup with absorption in 4 π and counting efficiency near 100%. Activated germanium has been integrated succesfully in the LTD setup by thermal decomposition of GeH4.

A possibility to search for elementary particles as dark matter candidates is to detect elastic scattering with cryogenic detectors. For the interpretation of the data one has to determine the detector response to nuclear recoils, the so-called quenching factors. They can differ for the heat-, for the scintillation- and for the ionization-signal and can be measured by scattering of neutrons. The CRESST- and the EDELWEISS-collaborations have set up a neutron scattering facility for cryogenic detectors at the tandem-accelerator of the Munich ‘Maier-Leibniz-Labor.’ The scattering angle and the time-of-flight of the neutrons are measured by an array of liquid scintillator cells. The pulsed high energy (11 MeV) neutron beam is created by nuclear reaction of a 11B on a H2-gas target. The set-up and the results of first tests are presented.

A slight deviation from linearity has been detected for single aluminum superconducting tunnel junction (Al-STJ) detectors in the energy range between E=1.74 keV and E=6.49 keV. The nonlinearity can be explained by the escape of recombination phonons into the substrate. Varying the size of the junction shows that the recombination of the quasiparticles takes place after their diffusive propagation across the junction. Pulse shape analysis allows to identify background events that are caused by photo-and Auger-electron propagation. For a detector system based on a Al-STJ with a Pb absorber pulse shape analysis allows to separate events related to absorption in the STJ and in the absorber.

With the simultaneous measurement of the temperature signal of a CaWO4 absorber crystal and the scintillation light, it is possible to reject the gamma and electron background in the search for dark matter particles. We report on an alternative new light detector design for the CRESST experiment. For the light detector we use iridium/gold phase transition thermometers with a special circular structure and an Al phonon collector on a silicon substrate. With this detector an energy threshold of 22.3 eV on a 5 σ level was achieved. The light detector was tested in coincidence with a phonon measurement of a 300 g CaWO4 crystal. The phonons from the CaWO4 crystal were measured with an Ir/Au thermometer with a transition temperature of 32 mK.

Results of the CRESST experiment at Gran Sasso using 262 g sapphire calorimeters with tungsten phase transition thermometers are presented. Calibration and analysis methods are described. Data taken in 2000 have been used to place limits on WIMP dark matter particles in the galactic halo. The sapphire detectors are especially sensitive for low-mass WIMPS with spin-dependent interaction and improve on existing limits in this region.

Data taken by CRESST in 2000 with a cryogenic detector system based on 262 g sapphire crystals is used to place limits on WIMP dark matter in the Galactic Halo. The detector is especially sensitive for low-mass WIMPS with spin-dependent cross sections and improves on existing limits in this region. CRESST is now preparing for a second phase, which will use a 10 kg detector consisting of 300 g CaWO4 crystals with simultaneous detection of phonons and scintillation light to reduce background.

Data taken by CRESST with a cryogenic detector system based on 262 g sapphire crystals has been used to place limits on WIMP dark matter in the Galactic Halo. The experiment was especially sensitive for low-mass WIMPs with spin-dependent cross sections and improves on existing limits in this region. © 2002 Elsevier Science B.V. All rights reserved.

The CRESST experiment seeks hypothetical WIMP particles that could account for the bulk of dark matter in the Universe. The detectors are cryogenic calorimeters in which WIMPs would scatter elastically on nuclei, releasing phonons. The first phase of the experiment has successfully deployed several 262 g sapphire devices in the Gran Sasso underground laboratories. A main source of background has been identified as microscopic mechanical fracturing of the crystals, and has been eliminated, improving the background rate by up to three orders of magnitude at low energies, leaving a rate close to one count per day per kg and per keV above 10 keV recoil energy. This background now appears to be dominated by radioactivity, and future CRESST scintillating calorimeters which simultaneously measure light and phonons will allow rejection of a great part of it., To appear in the proceedings of the CAPP2000 Conference, Verbier, Switzerland, July, 2000 (eds J. Garcia-Bellido, R. Durrer, and M. Shaposhnikov)

CRESST II is an experiment for direct WIMP search, using cryogenic detectors. The ratio of the two signals (temperature rise and scintillation light) measured for each interaction is an excellent parameter for discrimination of radioactive background. The main remaining background is the neutron flux present at the experimental site, since neutrons produce the same signals as WIMPs do. Based on Monte Carlo simulations the present work shows how neutrons from different origins affect CRESST and which measures have to be taken into account to reach the goal sensitivity., 2 pages, to appear in IAU Symposium 220, "Dark Matter in Galaxies", eds. Stuart Ryder, D.J. Pisano, Mark Walker & Ken Freeman, Publ. Astron. Soc. Pac