Techniques for nuclear and particle physics experiments pdf


 

the experiment, learning the relevant techniques, setting up and troubleshooting principal types of detectors used in nuclear and particle physics experiments. Techniques for Nuclear and Particle Physics Experiments Digitally watermarked, DRM-free; Included format: PDF; ebooks can be used on all reading devices. The first € price and the £ and $ price are net prices, subject to local VAT. Prices indicated with * include VAT for books; the €(D) includes 7% for. Germany, the.

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Techniques For Nuclear And Particle Physics Experiments Pdf

Techniques for Nuclear and Particle. Physics Experiments. A How-to Approach. Second Revised Edition. With Figures, 40 Tables and Numerous Worked. Techniques for nuclear and particle physics experiments. 1. Particles (N^cit*j pbysics)-Techaique. 2. Particles (Nuclear physicsJ-Erpcrimcnu. 3. Nuclear physics-. I have been teaching courses on experimental techniques in nuclear and particle physics to master students in physics and in engineering for many years.

Elementary-Particle Physics. It is also important to identify the type of particle: electron, muon. Thus the detectors, which determine the path, the energy, and the particle type. The development and construction of these detec- tors, and the analysis of the data produced, are the province of the particle experimentalist. The strong interest in rare processes such as W and Z production in the recent CERN experiments and the need to characterize events completely have led to the development of detec- tors sensitive to almost the total solid angle. At all accelerators but particularly at particle colliders it is essential to provide detectors capable of making the fullest use of the particle beams. A wide range of detectors exists including the small but often sophisticated instru- ments designed for fixed-target work, the large detectors used tor recording rare events such as the interactions of neutrinos or the decays of nucleons, and the large collider detectors that provide almost complete angular coverage and characterization of the interactions occurring in these machines. The following discussion. However, later in this chapter in the section on Detectors in Fixed-Target Experiments we present some highlights of the detectors used in these experiments. And in the final section of this chapter, we discuss experiments that do not use accelerators. As an introduction to large detectors.

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Consequently, fixed- target experiments generally appear as a linear sequence of detector elements downstream from the target, as Figure 6. We return to fixed-target detectors in a later section.

The larger detectors constitute major facilities, with a lifetime of usage of typically more than 10 years. The lower-energy pion tracks are curved more strongly by the magnetic field. Unlike the early pioneering experiments of parti- cle physics, a modern experiment may well require the simultaneous collaboration of several hundred physicists from 20 or more institu- tions.

These major facilities require resources comparable with those used in the construction of the parent accelerator. This implies that the detector should function over the largest possible angular range, measure with the best attainable precision, be provided with instrumentation to identify particle characteristics, and simultaneously provide a wide range of cross checks to protect against measurement artifacts. Additionally for use with hadron colliders, detectors must be able to extract interesting classes of physics events from backgrounds of events perhaps a hundred million times more frequent.

Statistics and the Treatment of Experimental Data

Note the enormous size of the detector compared with that of the person standing at its lower right side. A wide range of techniques serves to measure the position and magnitude of these ionization trails. The magnitude of this energy loss per unit length is a measure of particle velocities. In general this technique differ- entiates velocities only for relatively small particle energies.

Measurement of this curvature permits the mo- menta of these tracks to be determined. The particle's energy can be calculated from its momentum if the mass is known. The intensity and characteristics of these radiations can serve as the basis of a velocity measurement.

The energy of the original electron or photon is ultimately completely converted into ionization by these processes. Measurement of this converted energy in a sufficiently thick block of material determines the total incident electromagnetic energy and constitutes a calorimetric shower-energy measurement.

A detector constructed to make use of this property is an electromagnetic calorimeter. This again results in the production of intense cores of ionized atoms. The total energy of the incident particles can be measured from the total energy deposited in the form of ionization.

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Hadronic cascades can be differentiated from the electromagnetic cascades that develop in much thinner layers of material.

The technique of measurement is known as hadron calorim- etry. Typically a hadron calorimeter might require a thickness of 3 to 4 feet of instrumented steel with a total weight of hundreds of tons.

The characteristics of these detectors have many features in common and share similar design architectures. The detectors for collider experiments are based on a series of concentric shells or layers, one behind the other, each of which is devoted to some particular aspect or aspects of the detection process.

The initial detector layers are used to characterize the charged-particle component and are designed to be nondestructive, i. The outer layer of the calorimeter or an additional detection layer is frequently used to detect muons.

As mentioned earlier, energetic muons are usually the only particles that can reach this outermost layer. Inevitably as the layered levels of detection systems are built up, a detector will become large and correspondingly complex and expen- sive.

A prime objective of detector development is, therefore' to keep detection systems as compact as possible and to combine detection roles whenever possible. Additional demands are imposed on detector systems associated with hadron colliders by the high ambient radiation levels at the detector and by the fact that events of interest may be separated only by short times from uninteresting background events.

Summarized below are the elements or layers constituting a typical modern detector system and some of the ongoing research and development aimed at maximizing present or future detector capabili- ties. Close-in Detection: Vertex Detectors A fraction of the particles emerging from a collision point decay in flight at distances as close as 0.

Therefore use can be made of charged-particle detectors with high spatial resolution that are placed as close to the interaction point as possible.

The first such vertex detector for collider work was recently con- structed to operate with the Mark It detector at the PEP collider at the Stanford Linear Accelerator Center.

Several such detectors are now being constructed or are operating at electron-positron and proton- antiproton colliders. The principles of operation of these track detectors are described below. The chambers are typically only about 10 cm in radius, are fabricated with fine subdivisions to provide separation between adjoining tracks that might otherwise overlap, are aligned with great precision about 0.

The second-generation vertex detectors now under development are based on modern silicon semiconductor technology. This technology has already been used successfully on a small scale in experiments designed to measure decays of short-lived particles.

In these experiments the target is constructed of microstrips' and a detailed history of events occurring within these active targets can be recorded.

Prelirrunary tests have been made and have established the feasibility of the proposed vertex detectors. Full-scale detectors should come into operation during the next 5 years. Three approaches are being tried: 1 the use of packages of long thin silicon strips with widths of about 0. The handling, precision alignment, and electronic readout of such miniaturized devices present fascinating but soluble problems.

With reasonable confidence this second generation of detectors should pro- vide previsions an order of magnitude better than those currently obtainable. Charged-Particle Tracking Chambers In a typical collider detector, beyond the vertex detector are charged-particle tracking chambers. These chambers serve to measure the directions and curvatures of the paths of the individual particles.

These paths are called tracks. The principle of operation of a multiwire drift chamber is shown in Figure 6.

The first such devices were coarse and measured only a few tracks. Modern devices are fine "rained in subdivision and may provide over a hundred measured points to a track. The resulting image is almost of photographic quality and is reminiscent, even though produced at electronic speeds, of the superb track detection provided in bubble chambers.

With some additional effort and with certain possible compromises these detectors can also be used to measure the ionization of the produced tracks. An elegant variant of this detection method is to remove the fine grid of wires and to drift the ionization with a collection electric field to the end caps, where the arrival positions of the ionization are measured and also the arrival times and the degree of ionization.

In a drift chamber, slender wires are strung parallel to each other in a volume of gas. When a charged particle passes through the gas it leaves a track of ionized gas molecules and electrons. Electrons are attracted by the electrical voltage on the wires, and when they reach the wire they send an electrical pulse down the wire.

Those pulses are collected and amplified electronically and recorded on magnetic tape. The position of the track is given roughly by knowing the wire that gave the signal.

But a more accurate position is obtained knowing the time the electrons took to drift to the wire, hence the name drift chamber. This system. Charged-particle tracking detectors are often immersed in a magnetic field in order to make it possible, from measurements of the track curvatures, to determine the signs of the charges and the momenta of the particles.

Magnetic fields in the range of several kilogauss to several tens of kilogauss are used. The larger the field, the more the tracks curve, and the easier it is to measure the track momentum.

To provide the highest possible magnetic fields, it is desirable to use superconducting coils to carry the required large currents. Although a number of these coils have been constructed and successfully oper- ated, the technology of fabrication is demanding, and further research is desirable. Next in sequence beyond the tracking chamber there may be a detector layer that is used to identify the nature of the charged particles whether they are electrons protons, pions, kaons, or muons.

This region is still required to be nondestructive and thus to contain little material. Napolitano, 2nd ed. Academic Press, Leo, 2nd ed. Ferbel, 2nd ed. Mandel, Dover ed. Lyons, Cambridge University Press, See also the list of free online resources below. Handouts Writeups handed out in class are also available here as PDF files. Material will be added through the course of the semester. To help with safe handling and operation, students are given a lecture in radiation safety where they learn about types and risks of ionizing radiation, units and administrative limits, fundamental protection principles, and responsibilities.

It is extremely important that you always follow the lessons learned in this class and keep your safety and that of others always at the forefront.

For your reference, the slides of a radiation safety lecture are made available. For a more detailed introduction see this publication on Geiger tube theory from Centronic.

A comprehensive discussion of photomultiplier tube theory, design, and application can be found in the classic RCA Photomultiplier Manual , freely available as a scanned file in various formats and from many sources. The Hamamatsu manual Photomultiplier Tubes Basics and Applications is an even more extensive resource on photomultipliers, scintillators, and applications that can be consulted whenever more details on photomultiplier operation are desired.

A briefer introduction is available in the Wikipedia entry on photomultiplier. Document AN34 - Experiments in Nuclear Science , which can be downloaded from the ORTEC library hard copies of earlier editions are available in the labs , has descriptions of slightly different versions of several of the experiments performed in this class, with explanations of the equipment and methods.

In particular, a description of the operation and characteristics of NaI Tl gamma-ray detectors and an explanation for the different features of the pulse-height energy spectra obtained with such detectors is given in Experiment 3 Gamma-Ray Spectroscopy Using NaI Tl , Section 3.

See also pp.

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