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"Zavattini, G"
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Intrinsic mirror noise in Fabry–Perot based polarimeters: the case for the measurement of vacuum magnetic birefringence
Although experimental efforts have been active for about 30 years, a direct laboratory observation of vacuum magnetic birefringence, due to vacuum fluctuations, still needs confirmation: the predicted birefringence of vacuum is \\[\\Delta n = 4.0\\times 10^{-24}\\] @ 1 T. Key ingredients of a polarimeter for detecting such a small birefringence are a long optical path within the magnetic field and a time dependent effect. To lengthen the optical path a Fabry–Perot is generally used with a finesse ranging from \\[{{\\mathscr {F}}} \\approx 10^4\\] to \\[{{\\mathscr {F}}} \\approx 7\\times 10^5\\]. Interestingly, there is a difficulty in reaching the predicted shot noise limit of such polarimeters. We have measured the ellipticity and rotation noises along with Cotton-Mouton and Faraday effects as a function of the finesse of the cavity of the PVLAS polarimeter. The observations are consistent with the idea that the cavity mirrors generate a birefringence-dominated noise whose ellipticity is amplified by the cavity itself. The optical path difference sensitivity at \\[10\\;\\hbox {Hz}\\] is \\[S_{\\Delta {{\\mathscr {D}}}=6\\times 10^{-19}\\;\\hbox {m}/\\sqrt{\\mathrm{Hz}}\\], a value which we believe is consistent with an intrinsic thermal noise in the mirror coatings. Our findings prove that the continuous efforts to increase the finesse of the cavity to improve the sensitivity has reached a limit.
Journal Article
A polarisation modulation scheme for measuring vacuum magnetic birefringence with static fields
A novel polarisation modulation scheme for polarimeters based on Fabry–Perot cavities is presented. The application to the measurement of the magnetic birefringence of vacuum with the HERA superconducting magnets in the ALPS-II configuration is discussed.
Journal Article
Erratum to: A polarisation modulation scheme for measuring vacuum magnetic birefringence with static fields
In the original article unfortunately we missed two typos in the equation for
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at the top of the fourth page of the article.
Journal Article
The Role of Parents’ Attachment Configurations at Childbirth on Marital Satisfaction and Conflict Strategies
This study explores the role of adult attachment configurations on marital satisfaction and conflict strategies during the transition to parenthood in a sample of 206 participants, 104 new parents and 102 childless by choice. All participants were administered measures of dyadic satisfaction and conflict strategies at two stages (during pregnancy and after 8 months, when the child was 6 months old). In prospective parents, the participants’ adult attachment configurations were also investigated in line with Crowell’s model. Results showed a decline in satisfaction and a lower use of cooperative conflict strategies for new parents. Secure specific attachment configurations appeared predictable of better satisfaction during the transition to parenthood. Insecure specific attachment configurations were predictable of a lower use of the cooperative strategy of integrating. Results were also explored in terms of the couple’s matching of attachment configurations. Overall, findings showed that in order to study a couple’s functioning it is important to consider the weight of each partner’s attachment configuration.
Journal Article
What Makes Us Stay Together?
In recent years commentators have speculated on the \"collapse\" of the couple and the family, highlighting the increasing fragility of couple relationships making them vulnerable to crises and break ups. Now, more than ever, and prompted by changes that have shaken our assumptions about socio/cultural context, the reasons that make couple relationships unstable are sought in the negotiations and redefinitions required by the changes themselves. New types of families are emerging and consequently new issues are being raised about the dynamics of family relationships. This book underlines the role of attachment as a central motivational system in couple relationships, and focuses on the relationship between past and present experiences in determining choices, perceptions, and feelings in couple relationships. It considers what other motivational systems interact with attachment in constituting a couple's dynamics, and looks at aspects more directly experienced by couples: in particular, how they feel about their relationship, especially in terms of the degree of intimacy between them (something that attachment theorists might look at in evaluating how \"good\" a relationship is).
eBook
Discovery of an X-ray afterglow associated with the γ-ray burst of 28 February 1997
Researchers report the detection of an X-ray afterglow associated with the gamma-ray burst of Feb 28, 1997--the first such detection for any gamma-ray burst. The X-ray transient was found to contain a significant fraction of the total energy of the gamma-ray burst.
Journal Article
Transient optical emission from the error box of the γ-ray burst of 28 February 1997
For almost a quarter of a century
1
, the origin of γ-ray bursts— brief, energetic bursts of high-energy photons—has remained unknown. The detection of a counterpart at another wavelength has long been thought to be a key to understanding the nature of these bursts (see, for example, ref. 2), but intensive searches have not revealed such a counterpart. The distribution and properties of the bursts
3
are explained naturally if they lie at cosmological distances (a few Gpc)
4
, but there is a countervailing view that they are relatively local objects
5
, perhaps distributed in a very large halo around our Galaxy. Here we report the detection of a transient and fading optical source in the error box associated with the burst GRB970228, less than 21 hours after the burst
6,7
. The optical transient appears to be associated with a faint galaxy
7,8
, suggesting that the burst occurred in that galaxy and thus that γ-ray bursts in general lie at cosmological distance.
Journal Article
The PVLAS experiment: detecting vacuum magnetic birefringence
The PVLAS collaboration is presently assembling a new apparatus to detect vacuum magnetic birefringence. This property is related to the structure of the QED vacuum and is predicted by the Euler-Heisenberg-Weisskopf effective Lagrangian. It can be detected by measuring the ellipticity acquired by a linearly polarised light beam propagating through a strong magnetic field. Here we report results of a scaled-down test setup and briefly describe the new PVLAS apparatus. This latter one is in construction and is based on a high-sensitivity ellipsometer with a high-finesse Fabry-Perot cavity (> 4×105) and two 0.8 m long 2.5 T rotating permanent dipole magnets. Measurements with the test setup have improved by a factor 2 the previous upper bound on the parameter Ae, which determines the strength of the nonlinear terms in the QED Lagrangian: Ae(PVLAS) < 3.3 × 10−21 T−2 95% c.l.
Journal Article
222Rn emanation measurements for the XENON1T experiment
The selection of low-radioactive construction materials is of utmost importance for the success of low-energy rare event search experiments. Besides radioactive contaminants in the bulk, the emanation of radioactive radon atoms from material surfaces attains increasing relevance in the effort to further reduce the background of such experiments. In this work, we present the 222Rn emanation measurements performed for the XENON1T dark matter experiment. Together with the bulk impurity screening campaign, the results enabled us to select the radio-purest construction materials, targeting a 222Rn activity concentration of 10μBq/kg in 3.2t of xenon. The knowledge of the distribution of the 222Rn sources allowed us to selectively eliminate problematic components in the course of the experiment. The predictions from the emanation measurements were compared to data of the 222Rn activity concentration in XENON1T. The final 222Rn activity concentration of (4.5±0.1)μBq/kg in the target of XENON1T is the lowest ever achieved in a xenon dark matter experiment.
Journal Article