John Dainton

The role of polarized positrons and electrons in revealing fundamental interactions at the Linear Collider

The proposed International Linear Collider (ILC) is well-suited for discovering physics beyond the Standard Model and for precisely unraveling the structure of the underlying physics. The physics return can be maximized by the use of polarized beams. This report shows the paramount role of polarized beams and summarizes the benefits obtained from polarizing the positron beam, as well as the electron beam. The physics case for this option is illustrated explicitly by analyzing reference reactions in different physics scenarios. The results show that positron polarization, combined with the clean experimental environment provided by the linear collider, allows to improve strongly the potential of searches for new particles and the identification of their dynamics, which opens the road to resolve shortcomings of the Standard Model. The report also presents an overview of possible designs for polarizing both beams at the ILC, as well as for measuring their polarization.

Deep inelastic electron-nucleon scattering at the LHC

The physics, and a design, of a Large Hadron Electron Collider (LHeC) are sketched. With high luminosity, 1033cm-2s-1, and high energy, s1/2=1.4TeV, such a collider can be built in which a 70GeV electron (positron) beam in the LHC tunnel is in collision with one of the LHC hadron beams and which operates simultaneously with the LHC. The LHeC makes possible deep-inelastic lepton-hadron (ep, eD and eA) scattering for momentum transfers Q2 beyond 106GeV2 and for Bjorken x down to the 10-6. New sensitivity to the existence of new states of matter, primarily in the lepton-quark sector and in dense partonic systems, is achieved. The precision possible with an electron-hadron experiment brings in addition crucial accuracy in the determination of hadron structure, as described in Quantum Chromodynamics, and of parton dynamics at the TeV energy scale. The LHeC thus complements the proton-proton and ion programmes, adds substantial new discovery potential to them, and is important for a full understanding of physics in the LHC energy range.

On the energy dependence of the deep-inelastic diffractive cross section

The importance of the dependence upon Bjorken-x of the cross section for deep-inelastic ep diffraction is emphasized. It is suggested that an accurate measurement of a comparison of the Bjorken-x dependence of this cross section with that of the totally inclusive ep cross section may be the best way of determining the properties of the pomeron and whether they are universal and thus consistent with factorization. Results of such a comparison in the form of a measurement of the ratio of the deep-inelastic diffractive and total cross sections are reviewed and discussed. The x dependence of the measure of the total contribution of diffraction to deep-inelastic scattering is also presented and its significance stated.

Development of the kaon tagging system for the NA62 experiment at CERN

The NA62 experiment at CERN aims to make a precision measurement of the ultra-rare decay K+→π+νν¯, and relies on a differential Cherenkov detector (KTAG) to identify charged kaons at an average rate of 50 MHz in a 750 MHz unseparated hadron beam. The experimental sensitivity of NA62 to K-decay branching ratios (BR) of 10−11 requires a time resolution for the KTAG of better than 100 ps, an efficiency better than 95% and a contamination of the kaon sample that is smaller than 10−4. A prototype version of the detector was tested in 2012, during the first NA62 technical run, in which the required resolution of 100 ps was achieved and the necessary functionality of the light collection system and electronics was demonstrated.

DIAMOND fall-out seen from outside

May I try to highlight the issues that have arisen following the debacle over the UK governments decision about where Britains new synchrotron source, previously known as DIAMOND, should be located The eventual decision (April p5)to site the new £550m facility at the Rutherford Appleton Laboratory in Oxfordshire – rather than at the Daresbury Laboratory in Cheshire – is one, I believe, about which all physicists should be concerned. I make my comments as a particle physicist from an international scientific perspective, and as someone who worked at Daresbury when it flourished as a particle-physics centre and spawned UK synchrotron-radiation science at the NINA synchrotron.

John Riley Holt. 15 February 1918 — 6 January 2009

John Riley Holt was an experimental physicist who dedicated his working life to research in nuclear and particle physics at the University of Liverpool. He was born in 1918 in Runcorn, Cheshire, and in 1938 was awarded a first-class honours degree in physics at Liverpool University. He obtained his PhD in 1941 and became a member of Sir James Chadwick’s team working on the UK atomic weapon project. After the war he developed several new experimental techniques, which he used to make a systematic study of the deuteron stripping process with the use of the Liverpool cyclotron. After the Liverpool synchro-cyclotron became operational in 1954 he initiated a programme of precision measurements of cross-sections for proton–proton and pion–proton scattering. After the first observation of parity violation in 1957, his group completed an important experiment that observed parity violation in muon decay. When the construction of an electron synchrotron (NIN A, at the Daresbury Laboratory) was proposed, he became leader of the magnet design team. As NIN A became operational in 1966, John established a group to measure the cross-sections for the photoproduction of neutral and charged pions. The group then developed a collaboration with colleagues in other universities to measure the spin dependence of cross-sections for meson photoproduction by using a polarized photon beam and a polarized proton target. Before his retirement he contributed to the design of the experiment to determine the spin structure of the proton, performed by the European Muon Collaboration.

Further notes on the centenary of superconductivity

The articles in your special issue marking the centenary of superconductivity were interesting and quite rightly included one that describes the neglected work of the London brothers (The forgotten brothers April 2010 pp26–29).

Inclusive photoproduction of rho(0), K*(0) and phi mesons at HERA H1 Collaboration

Inclusive non-diffractive photoproduction of rho(770)(0), K*(892)(0) and phi(1020) mesons is investigated with the H1 detector in ep collisions at HERA. The corresponding average gamma p centre-of-mass energy is 210 GeV. The mesons are measured in the transverse momentum range 0.5 < p(T) < 7 GeV and the rapidity range vertical bar y(lab)vertical bar < 1. Differential cross sections are presented as a function of transverse momentum and rapidity, and are compared to the predictions of hadroproduction models

Let's hear it for HERA

Physics World is right to highlight the financial plight of UK particle physics by reporting the request from the Particle Physics and Astronomy Research Council (PPARC) for an extra £60m from 1998 (June p6). One hopes that the government will agree that such funding is essential to ensure the survival of the subject in the UK, and then make the funds available.

Electrons and quarks under the microscope

In the last decade, understanding of the fundamental nature of matter and its origin has been revolutionised. Particle physicists have established the picture known as the standard model, in which the present Universe has developed from an earlier epoch, within microseconds of the big bang. There it consisted of a set of fundamental entities known as quarks and leptons, which interact via four fundamental forces – electromagnetism, gravitation and the weak and strong nuclear forces.