Vibration Isolation Design for the Micro-X Rocket Payload

Micro-X is a NASA-funded, sounding rocket-borne X-ray imaging spectrometer that will allow high precision measurements of velocity structure, ionization state and elemental composition of extended astrophysical systems. One of the biggest challenges in payload design is to maintain the temperature of the detectors during launch. There are several vibration damping stages to prevent energy transmission from the rocket skin to the detector stage, which causes heating during launch. Each stage should be more rigid than the outer stages to achieve vibrational isolation. We describe a major design effort to tune the resonance frequencies of these vibration isolation stages to reduce heating problems prior to the projected launch in the summer of 2014.Comment: 6 pages, 7 figures, LTD15 Conference Proceeding

Magnetocaloric Materials and the Optimization of Cooling Power Density

The magnetocaloric effect is the thermal response of a material to an external magnetic field. This manuscript focuses on the physics and the properties of materials which are commonly used for magnetic refrigeration at cryogenic temperatures. After a brief overview of the magnetocaloric effect and associated thermodynamics, typical requirements on refrigerants are discussed from a standpoint of cooling power density optimization. Finally, a compilation of the most important properties of several common magnetocaloric materials is presented

Status of the micro-X sounding rocket x-ray spectrometer

Micro-X is a sounding rocket borne X-ray telescope that utilizes transition edge sensors to perform imaging spectroscopy with a high level of energy resolution. Its 2.1m focal length X-ray optic has an effective area of 300 cm 2 , a field of view of 11.8 arcmin, and a bandpass of 0.1-2.5 keV. The detector array has 128 pixels and an intrinsic energy resolution of 4.5 eV FWHM. The integration of the system has progressed with functional tests of the detectors and electronics complete, and performance characterization of the detectors is underway. We present an update of ongoing progress in preparation for the upcoming launch of the instrument.NASA Space Technology Research FellowshipUnited States. National Aeronautics and Space Administration (grant NNX10AE25G

Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely

Dilution refrigeration of multi-ton cold masses

Zsfassung in dt. Sprache3He/4He Verdünnungskryostaten stellen die einzige technische Möglichkeit zur kontinuierlichen Kühlung bei Temperaturen unter 250 mK dar. Derzeit in Planung befindliche Experimentanlagen erfordern die Kühlung von Massen in der Größenordnung mehrerer Tonnen und benötigen leistungsfähige Kühlsysteme, deren Kühlleistung unter 10 mK die Möglichkeiten heutiger Systeme beträchtlich übersteigt. Diese Arbeit beschäftigt sich mit der Entwicklung solcher Systeme.Eine neuartige, numerische Methode zur Berechnung der Kühlleistung eines Verdünnungskryostaten bekannten Designs wurde im Rahmen der vorliegenden Arbeit entwickelt. Diese Methode zieht nicht nur die Unterschiede zwischen realen und den in der Theorie üblicherweise behandelten idealen Wärmetauschern in Betracht, sondern ermöglicht auch die Berücksichtigung zusätzlicher Wärmelasten am Wärmetauscher und die Simulation transienten Verhaltens. Dieses numerische Modell wurde mittels experimenteller Daten verifiziert, die aus dem Betrieb eines vom Autor entwickelten Verdünnungskryostaten gewonnen wurden. Weiters wird die Bestimmung der minimalen Wärmelast, die von einem Kühlsystem eines Tieftemperaturexperiments abgeführt werden muß, behandelt. Die Ergebnisse dienen der Berechnung der erforderlichen Kühlleistung zukünftiger Großexperimente.Basierend auf der im Bau und Betrieb des Verdünnungskryostaten gewonnenen Erfahrung wurden Konstruktionsregeln für derartige Kühlsysteme abgeleitet. Diese wurden bei der Auslegung eines Kühlsystems für EURECA, eines europäischen Detektors für dunkle Materie, angewandt, wobei zusätzlich den Forderungen nach geringem radioaktivem Hintergrund und den aus dem Betrieb in unterirdischen Laboratorien resultierenden Einschränkungen Rechnung getragen wurde.Diese Arbeit wurde von CERN und vom Österreichischen Bundesministerium für Bildung, Wissenschaft und Kultur finanziert.Dilution refrigeration is the only means to provide continuous cooling at temperatures below 250 mK. Future experiments featuring multi-ton cold masses require a new generation of dilution refrigeration systems, capable of providing a heat sink below 10 mK at cooling powers which exceed the performance of present systems considerably. This thesis presents some advances towards dilution refrigeration of multi-ton masses in this temperature range.A new method using numerical simulation to predict the cooling power of a dilution refrigerator of a given design has been developed in the framework of this thesis project. This method does not only allow to take into account the differences between an actual and an ideal continuous heat exchanger, but also to quantify the impact of an additional heat load on an intermediate section of the dilute stream. In addition, transient behavior can be simulated. The numerical model has been experimentally verified with a dilution refrigeration system which has been designed, built and tested at CERN in the framework of this doctoral thesis project. Furthermore, the determination of the residual heat load to the cold mass of a very low temperature (VLT) experiment is addressed. The results of this analysis can be used to predict the required cooling power for large future experiments. Based on the experience gained with the dilution refrigeration system at CERN, design rules for large dilution refrigerators have been derived.They are consequently used in a design and feasibility study of a refrigeration system, which is tailored for the future cryogenic dark matter search EURECA and meets the requirements of low-background experiments and operation in remote underground laboratories.This doctoral thesis project has been funded CERN and by the Austrian Federal Ministry for Education, Science and Culture.16

Designing for manned spaceflight on the example of the ISS crew refrigerator and freezer rack (RFR)

Zsfassung in dt. Sprache14

Theoretical Models for the Cooling Power and Base Temperature of Dilution Refrigerators

He-3/He-4 dilution refrigerators are widely used for applications requiring continuous cooling at temperatures below approximately 300 mK. Despite of the popularity of these devices in low temperature physics, the thermodynamic relations underlying the cooling mechanism of He-3/He-4 refrigerators are very often incorrectly used. Several thermodynamic models of dilution refrigeration have been published in the past, sometimes contradicting each other. These models are reviewed and compared with each other over a range of different He-3 flow rates. In addition, a new numerical method for the calculation of a dilution refrigerator's cooling power at arbitrary flow rates is presented. This method has been developed at CERN's Central Cryogenic Laboratory. It can be extended to include many effects that cannot easily be accounted for by any of the other models, including the degradation of heat exchanger performance due to the limited number of step heat exchanger elements, which can be considerable for some designs. Finally, the limitations of applying the results obtained with idealized thermodynamic models to actual dilution refrigeration systems are discussed

Analysis of the low-energy electron-recoil spectrum of the CDMS experiment

We report on the analysis of the low-energy electron-recoil spectrum from the CDMS II experiment using data with an exposure of 443.2 kg-days. The analysis provides details on the observed counting rate and possible background sources in the energy range of 2–8.5 keV. We find no significant excess of a peaked contribution to the total counting rate above the background model, and compare this observation to the recent DAMA results. In the framework of a conversion of a dark matter particle into electromagnetic energy, our 90% confidence level upper limit of 0.246  events/kg/day at 3.15 keV is lower than the total rate above background observed by DAMA. In absence of any specific particle physics model to provide the scaling in cross section between NaI and Ge, we assume a Z2 scaling. With this assumption the observed rate in DAMA remains higher than the upper limit in CDMS. Under the conservative assumption that the modulation amplitude is 6% of the total rate we obtain upper limits on the modulation amplitude a factor of ∼2 lower than observed by DAMA, constraining some possible interpretations of this modulation.National Science Foundation ((Grant Nos. AST-9978911, PHY-0542066, PHY-0503729, PHY-0503629, PHY-0503641, PHY- 0504224, PHY-0705052, PHY-0801536, PHY-0801708, PHY-0801712 and PHY-0802575)United States Department of Energy (Contracts DE-AC03-76SF00098, DE-FG02- 91ER40688, DE-FG02-92ER40701, DE-FG03- 90ER40569, and DE-FG03-91ER40618)Swiss National Science Foundation (SNF Grant No. 20-118119

Progress on the Micro-X rocket payload

The Micro-X High Resolution Microcalorimeter X-ray Imaging Rocket is sounding rocket experiment that will combine a transition-edge-sensor X-ray-microcalorimeter array with a conical imaging mirror to obtain high-spectral-resolution images of extended and point X-ray sources. Our first target is the Puppis A supernova remnant, which will be observed in January 2011. The Micro-X observation of the bright eastern knot of Puppis A will obtain a line-dominated spectrum with up to 90,000 counts collected in 300 seconds at 2 eV resolution across the 0.3-2.5 keV band. Micro-X will utilize plasma diagnostics to determine the thermodynamic and ionization state of the plasma, to search for line shifts and broadening associated with dynamical processes, and seek evidence of ejecta enhancement. We describe the progress made in developing this payload, including the detector, cryogenics, and electronics assemblies. A detailed modeling effort has been undertaken to design a rocket-bourne adiabatic demagnetization refrigerator with sufficient magnetic shielding to allow stable operation of transition edge sensors, and the associated rocket electronics have been prototyped and tested