Transverse Diagnostics For High Energy Hadron Colliders

The Large Hadron Collider (LHC) is a circular synchrotron accelerator that will explore new Physics at the higher energies ever achieved, aiming to find the Higgs boson. The LHC is being built at CERN and by 2007 it will be ready to produce head-on collisions of protons at a centre-of-mass energy of 14 TeV. The employment of superconducting magnets for achieving high energies, the high luminosity required for physics, the limited dynamic aperture and the large energy stored in the beams will make the machine very challenging to operate, especially during the injection process and the energy ramp. Two particular problems will be a high sensitivity to beam losses and a relatively poor field quality requiring the use of many types of magnetic correction elements. This may lead to the inclusion of certain beam measurements in feedback loops, making special demands on the control system. The injection and acceleration of the LHC proton beams without particle losses and emittance blow up will require an accurate control of the beam parameters. The value of the betatron tune is about 63 units and needs to be controlled to a level of $\Delta Q = ±0.003$. Orbit excursions should be limited to less than 0.5 mm. The linear chromaticity should be limited to some units (nominal value $Q'_HV = 2$). This Thesis will be focused on the improvement of new instrumentation for the measurement of beam parameters that is compatible with LHC high intens ity running. In this sense, the importance for the performance of the accelerator of terms such as tune or chromaticity will be pointed out. This work can be considered to be divided into two differentiated parts: the tests performed to a potentially beam diagnostics device and the improvement of the sensitivity of an already existing monitor. However, behind both subjects there is a common objective: the need of implementing new sensitive and non destructive methods for measuring parameters of major importance to keep the beam within the tight tolerances imposed to the superconducting and high energy accelerator LHC

Gaia Early Data Release 3: Structure and properties of the Magellanic Clouds

We compare the Gaia DR2 and Gaia EDR3 performances in the study of the Magellanic Clouds and show the clear improvements in precision and accuracy in the new release. We also show that the systematics still present in the data make the determination of the 3D geometry of the LMC a difficult endeavour; this is at the very limit of the usefulness of the Gaia EDR3 astrometry, but it may become feasible with the use of additional external data. We derive radial and tangential velocity maps and global profiles for the LMC for the several subsamples we defined. To our knowledge, this is the first time that the two planar components of the ordered and random motions are derived for multiple stellar evolutionary phases in a galactic disc outside the Milky Way, showing the differences between younger and older phases. We also analyse the spatial structure and motions in the central region, the bar, and the disc, providing new insights into features and kinematics. Finally, we show that the Gaia EDR3 data allows clearly resolving the Magellanic Bridge, and we trace the density and velocity flow of the stars from the SMC towards the LMC not only globally, but also separately for young and evolved populations. This allows us to confirm an evolved population in the Bridge that is slightly shift from the younger population. Additionally, we were able to study the outskirts of both Magellanic Clouds, in which we detected some well-known features and indications of new ones

Research and Design of a Routing Protocol in Large-Scale Wireless Sensor Networks

无线传感器网络，作为全球未来十大技术之一，集成了传感器技术、嵌入式计算技术、分布式信息处理和自组织网技术，可实时感知、采集、处理、传输网络分布区域内的各种信息数据，在军事国防、生物医疗、环境监测、抢险救灾、防恐反恐、危险区域远程控制等领域具有十分广阔的应用前景。 本文研究分析了无线传感器网络的已有路由协议，并针对大规模的无线传感器网络设计了一种树状路由协议，它根据节点地址信息来形成路由，从而简化了复杂繁冗的路由表查找和维护，节省了不必要的开销，提高了路由效率，实现了快速有效的数据传输。 为支持此路由协议本文提出了一种自适应动态地址分配算——ADAR（AdaptiveDynamicAddre...As one of the ten high technologies in the future, wireless sensor network, which is the integration of micro-sensors, embedded computing, modern network and Ad Hoc technologies, can apperceive, collect, process and transmit various information data within the region. It can be used in military defense, biomedical, environmental monitoring, disaster relief, counter-terrorism, remote control of haz...学位：工学硕士院系专业：信息科学与技术学院通信工程系_通信与信息系统学号：2332007115216

XFEL Machine Protection System (MPS) Based on UTCA

For the operation of a machine like the 3 km long linearaccelerator XFEL at DESY Hamburg, a safety systemkeeping the beam from damaging components isobligatory. This machine protection system (MPS) mustdetect failures of the RF system, magnets, and othercritical components in various sections of the XFEL aswell as monitor beam and dark current losses, and react inan appropriate way by limiting average beam power,dumping parts of the macro-pulse, or—in the worstcase—shutting down the whole accelerator. It has toconsider the influence of various machine modes selectedby the timing system.The MPS provides the operators with clear indicationsof error sources, and offers the possibility to mask anyinput channel to facilitate the operation of the machine. Inaddition, redundant installation of critical MPScomponents will help to avoid unnecessary downtime.This document summarizes the requirements on themachine protection system and includes plans for itsarchitecture and for needed hardware components

High Level Software for the Commissioning of the European XFEL

The European X-Ray Free-Electron Laser (XFEL) will generate extremely short and intense X-ray flashes from the electron beam of a 2.1 km long superconducting linear accelerator. The commissioning and operation of the accelerator relies heavily on high level software for the automatization of measurements and procedures. The paper gives an overview of the ongoing work and highlights some new measurement techniques

Longitudinal Phase Space (LPS) Characterization of High Brightness Electron Beams at PITZ

Methodological studies to improve the LPS tomography of space-charge dominated electron beams were carried out at the Photo Injector Test facility at DESY in Zeuthen (PITZ). In the experimental procedure, initially, a 200 μm-wide horizontal slit was introduced before the booster to cut the beam to strongly reduce space charge effects. Next, the signal resolution of this truncated beam was improved by careful beta function control at the reference screen of momentum measurements. A combination of both steps enabled accurate measurement of minimum energy spread and better control of beam phase advance during booster phase scan, i.e. control of booster amplitude and phase scan range. After optimization of the experimental conditions, the momentum projections were fed to a tomographic reconstruction algorithm to obtain the reconstructed LPS. Finally, the noisy artifacts in LPS were addressed to further improve the results

Matching of a Space-Charge Dominated Beam into the Undulator of the THz SASE FEL at PITZ

The Photo Injector Test facility at DESY in Zeuthen (PITZ) is developing a THz SASE FEL as a prototype high repetition rate accelerator-based source for the THz-pumped, X-ray-probed experiments at the European XFEL. For the generation of THz pulses of mJ-level energy from SASE, an electron beam with a high charge (up to 4 nC) and high peak current (~200 A) will be injected into an LCLS-I undulator, which is currently being installed at the end of the photo-injector. The narrow vacuum chamber (11x5 mm) between the magnetic poles and the strong vertical focusing from the undulator, as well as the lack of beam diagnostics, have made it a challenge to match the space-charge dominated beam into the undulator without beam loss during the following transport. In this paper, boundary conditions of a matched electron beam will be discussed and the simulation and experimental study on our matching strategy will be presented

Experimental Slice Emittance Reduction at PITZ Using Laser Pulse Shaping

Free-electron lasers in the X-ray regime require a high-brightness electron beam, i.e. an electron beam with high current and low transverse emittance. At the Photo Injector Test facility at DESY in Zeuthen (PITZ) high-brightness electron sources are optimized for the use at FLASH and European XFEL. A low transverse emittance of the electron beam’s central part, which is assumed to be the lasing slices, is of particular interest for the efficient FEL operation. Over the past years a slice emittance measurement scheme has been developed at PITZ which employs an rf deflector and additional quadrupole magnets along the beamline to the standard measurement procedure for the projected emittance (single-slit scan). It allows measuring the slice emittance in a high-brightness photo injector. Transversely flat-top shaped laser pulses of different temporal distributions (Gaussian and flat-top) have been used to emit electrons, as well as transversely-truncated Gaussian laser pulses with temporal Gaussian shape. The paper shows that the lowest slice emittance in the injector is reached with a temporal flattop shape, or when using a transversely-truncated Gaussian shape