Experimental perspectives on the matter-antimatter asymmetry puzzle: developments in electron EDM and [Formula: see text] experiments

In the search for clues to the matter-antimatter puzzle, experiments with atoms or molecules play a particular role. These systems allow measurements with very high precision, as demonstrated by the unprecedented limits down to [Formula: see text] e cm on electron EDM using molecular ions, and relative measurements at the level of [Formula: see text] in spectroscopy of antihydrogen atoms. Building on these impressive measurements, new experimental directions offer potential for drastic improvements. We review here some of the new perspectives in those fields and their associated prospects for new physics searches. This article is part of the theme issue 'The particle-gravity frontier'.

Search for Dark Matter Axions with CAST-CAPP

The CAST-CAPP axion haloscope, operating at CERN inside the CAST dipole magnet, has searched for axions in the 19.74 μeV to 22.47 μeV mass range. The detection concept follows the Sikivie haloscope principle, where Dark Matter axions convert into photons within a resonator immersed in a magnetic field. The CAST-CAPP resonator is an array of four individual rectangular cavities inserted in a strong dipole magnet, phase-matched to maximize the detection sensitivity. Here we report on the data acquired for 4124 h from 2019 to 2021. Each cavity is equipped with a fast frequency tuning mechanism of 10 MHz/ min between 4.774 GHz and 5.434 GHz. In the present work, we exclude axion-photon couplings for virialized galactic axions down to g_aγγ = 8 × 10⁻¹⁴ GeV⁻¹ at the 90% confidence level. The here implemented phase-matching technique also allows for future large-scale upgrades.

Haloscopes aim at detecting axions by converting them into photons using high-quality resonant cavities, where the cavity resonance should be tuned with the unknown axion mass. Here, the authors improve exclusion limits using four phase-matched resonant cavities and a fast frequency scanning technique.

Minimizing plasma temperature for antimatter mixing experiments

The ASACUSA collaboration produces a beam of antihydrogen atoms by mixing pure positron and antiproton plasmas in a strong magnetic field with a double cusp geometry. The positrons cool via cyclotron radiation inside the cryogenic trap. Low positron temperature is essential for increasing the fraction of antihydrogen atoms which reach the ground state prior to exiting the trap. Many experimental groups observe that such plasmas reach equilibrium at a temperature well above the temperature of the surrounding electrodes. This problem is typically attributed to electronic noise and plasma expansion, which heat the plasma. The present work reports anomalous heating far beyond what can be attributed to those two sources. The heating seems to be a result of the axially open trap geometry, which couples the plasma to the external (300 K) environment via microwave radiation.

Recent Developments from on Antihydrogen Detection

The ASACUSA Collaboration at CERNs Antiproton Decelerator aims to measure the ground state hyperfine splitting of antihydrogen with high precision to test the fundamental symmetry of CPT (combination of charge conjugation, parity transformation, and time reversal). For this purpose an antihydrogen detector has been developed. Its task is to count the arriving antihydrogen atoms and therefore distinguish backgroundevents (mainly cosmics) from antiproton annihilations originating from antihydrogen atoms which are produced only in small amounts. A central BGO crystal disk with position sensitive read-out detects the annihilation and a surrounding two-layered hodoscope is used for tracking charged secondaries. The hodoscope has been recently upgraded to allow precise vertex reconstruction. A machine learning analysis based on measured antiproton annihilations and cosmic rays has been developed to identify antihydrogen events.

AEgIS at ELENA: outlook for physics with a pulsed cold antihydrogen beam

The efficient production of cold antihydrogen atoms in particle traps at CERN's Antiproton Decelerator has opened up the possibility of performing direct measurements of the Earth's gravitational acceleration on purely antimatter bodies. The goal of the AEgIS collaboration is to measure the value of g for antimatter using a pulsed source of cold antihydrogen and a Moiré deflectometer/Talbot-Lau interferometer. The same antihydrogen beam is also very well suited to measuring precisely the ground-state hyperfine splitting of the anti-atom. The antihydrogen formation mechanism chosen by AEgIS is resonant charge exchange between cold antiprotons and Rydberg positronium. A series of technical developments regarding positrons and positronium (Ps formation in a dedicated room-temperature target, spectroscopy of the n=1-3 and n=3-15 transitions in Ps, Ps formation in a target at 10 K inside the 1 T magnetic field of the experiment) as well as antiprotons (high-efficiency trapping of [Formula: see text], radial compression to sub-millimetre radii of mixed [Formula: see text] plasmas in 1 T field, high-efficiency transfer of [Formula: see text] to the antihydrogen production trap using an in-flight launch and recapture procedure) were successfully implemented. Two further critical steps that are germane mainly to charge exchange formation of antihydrogen-cooling of antiprotons and formation of a beam of antihydrogen-are being addressed in parallel. The coming of ELENA will allow, in the very near future, the number of trappable antiprotons to be increased by more than a factor of 50. For the antihydrogen production scheme chosen by AEgIS, this will be reflected in a corresponding increase of produced antihydrogen atoms, leading to a significant reduction of measurement times and providing a path towards high-precision measurements.This article is part of the Theo Murphy meeting issue 'Antiproton physics in the ELENA era'.

The ASACUSA antihydrogen and hydrogen program: results and prospects

The goal of the ASACUSA-CUSP collaboration at the Antiproton Decelerator of CERN is to measure the ground-state hyperfine splitting of antihydrogen using an atomic spectroscopy beamline. A milestone was achieved in 2012 through the detection of 80 antihydrogen atoms 2.7 m away from their production region. This was the first observation of 'cold' antihydrogen in a magnetic field free region. In parallel to the progress on the antihydrogen production, the spectroscopy beamline was tested with a source of hydrogen. This led to a measurement at a relative precision of 2.7×10^-9 which constitutes the most precise measurement of the hydrogen hyperfine splitting in a beam. Further measurements with an upgraded hydrogen apparatus are motivated by CPT and Lorentz violation tests in the framework of the Standard Model Extension. Unlike for hydrogen, the antihydrogen experiment is complicated by the difficulty of synthesizing enough cold antiatoms in the ground state. The first antihydrogen quantum states scan at the entrance of the spectroscopy apparatus was realized in 2016 and is presented here. The prospects for a ppm measurement are also discussed.This article is part of the Theo Murphy meeting issue 'Antiproton physics in the ELENA era'.

AEg̅IS latest results

The validity of the Weak Equivalence Principle (WEP) as predicted by General Relativity has been tested up to astounding precision using ordinary matter. The lack hitherto of a stable source of a probe being at the same time electrically neutral, cold and stable enough to be measured has prevented highaccuracy testing of the WEP on anti-matter. The AEg̅IS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) experiment located at CERN's AD (Antiproton Decelerator) facility aims at producing such a probe in the form of a pulsed beam of cold anti-hydrogen, and at measuring by means of a moiré deflectometer the gravitational force that Earth's mass exerts on it. Low temperature and abundance of the H̅ are paramount to attain a high precision measurement. A technique employing a charge-exchange reaction between antiprotons coming from the AD and excited positronium atoms is being developed at AEg̅IS and will be presented hereafter, alongside an overview of the experimental apparatus and the current status of the experiment

Towards the first measurement of matter-antimatter gravitational interaction

The AEgIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) is a CERN based experiment with the central aim to measure directly the gravitational acceleration of antihydrogen. Antihydrogen atoms will be produced via charge exchange reactions which will consist of Rydberg-excited positronium atoms sent to cooled antiprotons within an electromagnetic trap. The resulting Rydberg antihydrogen atoms will then be horizontally accelerated by an electric field gradient (Stark effect), they will then pass through a moiré deflectometer. The vertical deflection caused by the Earth's gravitational field will test for the first time the Weak Equivalence Principle for antimatter. Detection will be undertaken via a position sensitive detector. Around 103 antihydrogen atoms are needed for the gravitational measurement to be completed. The present status, current achievements and results will be presented, with special attention toward the laser excitation of positronium (Ps) to the n=3 state and the production of Ps atoms in the transmission geometry.

In-beam measurement of the hydrogen hyperfine splitting and prospects for antihydrogen spectroscopy

Antihydrogen, the lightest atom consisting purely of antimatter, is an ideal laboratory to study the CPT symmetry by comparison with hydrogen. With respect to absolute precision, transitions within the ground-state hyperfine structure (GS-HFS) are most appealing by virtue of their small energy separation. ASACUSA proposed employing a beam of cold antihydrogen atoms in a Rabi-type experiment, to determine the GS-HFS in a field-free region. Here we present a measurement of the zero-field hydrogen GS-HFS using the spectroscopy apparatus of ASACUSA's antihydrogen experiment. The measured value of νHF=1,420,405,748.4(3.4) (1.6) Hz with a relative precision of 2.7 × 10-9 constitutes the most precise determination of this quantity in a beam and verifies the developed spectroscopy methods for the antihydrogen HFS experiment to the p.p.b. level. Together with the recently presented observation of antihydrogen atoms 2.7 m downstream of the production region, the prerequisites for a measurement with antihydrogen are now available within the ASACUSA collaboration.

Improved Measurement of the π→eν Branching Ratio

A new measurement of the branching ratio R_{e/μ}=Γ(π^{+}→e^{+}ν+π^{+}→e^{+}νγ)/Γ(π^{+}→μ^{+}ν+π^{+}→μ^{+}νγ) resulted in R_{e/μ}^{exp}=[1.2344±0.0023(stat)±0.0019(syst)]×10^{-4}. This is in agreement with the standard model prediction and improves the test of electron-muon universality to the level of 0.1%.

[Management of the Legionella-link risk in a multicentre area's hospital: lessons learned of a six-year experience]

To reduce the Legionella-linked risk in the several sites of Sud-Francilien Hospital, following a hospital-acquired legionellosis case, a multidisciplinary working group performed an action plan monitored through Legionella pneumophila counts in hot water supply. From 2003 to the first half year 2009, positive points for Legionella pneumophila in the main sites of the hospital decreased from 85.71 to 28.00%, representing a significant reduction of 67.33%. Similar results were observed for three of the four establishments, whereas the last did not describe a pronounced reduction of Legionella pneumophila counts and showed constantly serogroup 1 strains. During this period, investigations of additional cases of legionellosis demonstrated a nosocomial transmission in one case in this last site. Multidisciplinary mobilization in management of Legionella-linked risk contributed to these results.

Épidémiologie et résistance aux antibiotiques de Streptococcus pneumoniae en Île de France en 2001

OBJECTIVE

The authors wanted to assess the level of Streptococcus pneumoniae antibiotic resistance in Ile de France.

METHOD

In 2001, 637 clinical strains of S. pneumoniae were prospectively collected from 32 microbiology laboratories.

RESULTS

Fifty one percent of strains were isolated from children under 15 years of age and 49% from adults. In children, 76% of strains came from otitis media, 20% from blood culture, in adults most strains (92%) came from blood culture. The overall prevalence of non-susceptible penicillin pneumococci was 61% higher in children (73%) than in adults (50%). Among the non-susceptible penicillin pneumococci 21.8% were resistant (CMI > 1 mg/l). Strains with decreased susceptibility to amoxicillin and cefotaxime were 38% and 17% respectively. Resistant strains to these two drugs (CMI > 2 mg/l) were rare 2.6% and 0.4% respectively. Among other antimicrobial agents, rate of resistance was 63% to erythromycin, 47% to cotrimoxazole, 40% to tetracycline, and 23% to chloramphenicol. The most frequent serogroups were serogroups 19 and 14, respectively 23% and 18%. Serotypes included in heptavalent vaccine covered 90% of children strains under 2 years of age.

CONCLUSIONS

The prevalence of resistance to penicillin was high in children particularly in otitis media pus (76%).

Surveillance of methicillin-resistant Staphylococcus aureus (MRSA) and Enterobacteriaceae producing extended-spectrum beta-lactamase (ESBLE) in Northern France: a five-year multicentre incidence study

In order to measure the incidence of methicillin-resistant Staphylococcus aureus (MRSA) and of Enterobacteriaceae producing extended-spectrum beta-lactamase (ESBLE), and to evaluate the impact of the national guidelines for multidrug-resistant bacteria (MDRB) prevention in hospitals of Northern France, a multicentre study was conducted for three months every year starting in 1996, in volunteer hospital laboratories. All clinical specimens positive for MRSA and ESBLE were prospectively surveyed. During the five-year surveillance period, the overall proportion of MRSA was 38.4% in the 28,534 strains of S. aureus, and that of ESBLE was 11.4% in the 6121 strains of Klebsiella pneumoniae and 47.7% in the 2353 strains of Enterobacter aerogenes. The overall incidence rates of clinical specimens positive for MRSA, ESBL-K. pneumoniae and E. aerogenes were 0.84. 0.05 and 0.12/1000 hospital-days (HD), respectively. In the 23 hospitals that participated in the survey every year, the proportion and incidence of ESBLE decreased. Hence, despite recommendations as for isolation precautions, MRSA remains poorly controlled and requires more effective measures.

[Comparative study of the BACTEC 9000 MB system and Lowenstein Jensen media for mycobacterial culture]

An automated system for mycobacteria culture, BACTEC 9000 MB, was compared with Lowenstein Jensen culture. On a total of 4,484 pulmonary and extrapulmonary human clinical samples, 126 (2.8%) were positive for mycobacteria on Lowenstein Jensen (LJ) medium; 105 (2.34%) were identified as Mycobacterium tuberculosis and 39 (1.10%) as non tuberculosis mycobacteria. The mean time of detection of Mycobacterium tuberculosis on the 131 positive samples was reduced to approximately ten days with BACTEC 9000 MB compared to the LJ (17.6 versus 27.38 days). Through the results of this comparative study, we confirmed that BACTEC 9000 MB is a more efficient system than LJ for culture detection of all mycobacteria from various sites samples.

Two cases of discitis due to Propionibacterium acnes

We report two cases of discitis due to Propionibacterium acnes and review previously published cases of bone and joint infections in which this organism was recovered as a pure culture. P. acnes is an anaerobic organism usually considered a normal inhabitant of the skin but capable of producing a variety of infections including discitis, osteitis, arthritis, and chest wall osteitis. Most patients were immunocompetent. A few infections occurred spontaneously, whereas others were secondary to a break in the skin or to implantation of foreign material into the body for instance during internal fixation of a fracture or arthroplasty. Cases of P. acnes chest wall infection have been reported in patients with palmoplantar pustulosis or chronic or multifocal osteitis, supporting a role for P. acnes in SAPHO syndrome.

Stability of nystatin in mouthrinses; effect of pH temperature, concentration and colloidal silver addition, studied using an in vitro antifungal activity

Alkaline low concentration nystatin mouthrinses extemporanely prepared can be used to treat oropharyngeal candidiasis in immunodeficient patients. However, their expiration dates are not distinctly determined. The stability of nystatin, added (as Mycostatine) at a concentration of 14,400 U/ml in 10-4N hydrochloric acid, purified water and 1.4% injectable sodium hydrogen carbonate with or without 0.002% colloidal silver (an antiseptic agent added because of its known antifungal potency) was studied after storage in tinted glass bottles at 5 degrees C and 22 degrees C over 11 days, and compared with reconstituted 100,000 U/ml aqueous Mycostatine oral suspension. At 2, 4, 7, 9, and 11 days after preparation. Samples were tested for pH, microbial contamination, and assayed by an in vitro microbiological test. Neither significant variation of pH nor microbial contamination were in evidence. Nystatin 14400 U/ml maintained at least 90% of its initial concentration for 4 days in acid at both temperatures, for 7 days (5 degrees C) and 4 days (22 degrees C) in aqueous and alkaline environments, for 9 days (5 degrees C) and 7 days (22 degrees C) in 1.4% injectable sodium hydrogen carbonate containing colloidal silver which showed an antifungal potency. The 100,000 U/ml aqueous Mycostatine oral suspension was stable for 9 days and 4 days at 5 degrees C and 22 degrees C respectively. An ambulant patient can keep a low concentration alkaline antifungal mouthrinse at home for a week at 5 degrees C.

[Bacteriologic monitoring of 1,000 units of human packed red blood cells for Yersinia enterocolitica]

Several reports of Yersinia enterocolitica (Ye) post-transfusion septicaemia have been recently published. In order to study the prevalence of Ye contamination of packed red blood cells (PRBC) we performed a post-transfusion control on 1,000 PRBC units. We did not find any Ye contamination. This is in accordance with the rarity of the reported cases. However as they are very serious, a prevention is necessary. As classical bacteriological techniques are not feasible, the only possibility is to decrease the PRBC conservation time and to select blood donors by a careful questioning about recent GI tract disturbances.

[Value of agglutination tests for the rapid identification of isolated streptococci in medical microbiology]

The clinical need for rapidly and correctly differentiating pathogenic streptococci into Lancefield groups prompted the development of rapid agglutination techniques by the direct colony method. Pastorex Streptogroupe (Diagnostics Pasteur, France) and Streptex (Wellcome Diagnostics, USA) were tested on 90 streptococcal isolates and compared with the identification obtained by conventional procedures. No cross-reactions were observed with any of the 33 strains of enterococci and of the seven strains representative of other genus among Gram-positive bacteria. When combined with colonial morphology and hemolytic reaction, both Pastorex and Streptex were specific tests for identifying beta-hemolytic streptococci, with Pastorex being slightly faster.

A five-generation family with sacral agenesis and spina bifida: possible similarities with the mouse T-locus

In man, a malformation that recalls some of the defects associated with T/t mutants in the mouse is sacral agenesis. We report on a family with a high incidence of sacral malformation, ranging from a complete absence of the sacrum (SA), with or without spina bifida aperta, to a spina bifida occulta (SBO) that could only be detected by x-ray. The condition appeared in a man with four children who were all affect, and thereafter, to varying degrees, in 17 of his 28 descendants. Segregation analysis has been performed in this family, using the Elston and Stewart transmission probability model [1971]. The two traits (SA and SBO) were first studied separated and then together. A fully penetrant major dominant gene is show to cause SA. When the phenotypes SA and SBO are considered together, Mendelian transmission is rejected. This could be explained genetically by two alternative hypotheses: genetic heterogeneity or a dominant major gene transmitted in excess by heterozygotes (tau Aa A = 0.896), suggesting a segregation distortion property of an allele at a T-like locus.