W Bozonunun Keşfi Üzerine Düşünceler

W Bozonunun Keşfi Üzerine Düşünceler

Thoughts on Discovery of the W Boson

03.03.2013

Mehmet Keçeci

W Bozon

Soldan Sağa: Carlo Rubbia, Simon van der Meer, Herwig Schopper, Erwin Gabathuler, Pierre Darriulat. CERN: 25 Ocak 1983

W bozonunun deneysel olarak bulunuşunun 30. yılındayız (24 Şubat 1983-2013) [1, 2]. ILC (International Linear Collider) ve CLIC (Compact Linear Collider) [3] ekiplerinin işbirliği bize daha neler söyleyecek [4]. 1984 yılı ise onlara Nobel Ödülü kazandırmıştır (The Nobel Prize in Physics 1984) [5].

W Boson

Zayıf etkileşimin taşıyıcıları (carrying the weak force) olan W, Z bozonlarından günümüzde Higgs bozonlarına [6, 7] doğru bir serüven yaşanmıştır.

Higgs

Öğrencilerime her sene Matematiğin Nobel ödülü olup olmadığını sorarım. Genelde biraz şaşırırlar.

Sonra olmadığını söyledikten sonra neden olmadığını sorarım. Çünkü bazen fizik ve matematik o kadar karıştırılıyor ki sanki ikisi de aynı anlamlar taşıyormuş gibi. Fiziğin matematiği veya matematiksel yöntemleri kullanması matematiğin verdiği anlamların tamamını vermesi anlamına asla ve asla gelmemektedir. Bunların temel felsefeleri farklıdır. Birinin kökeninde insan beyni diğerinin kökeninde evren vardır. Biri tamamen reele dayanır fakat reel olanı da olmayanı da kullanabilir. Diğeri ise tamamen reel olmayandan üretir ve reellik gibi bir sorunu yoktur. Kısaca birinin reellik sorunu varken diğerinin yoktur. Fakat her ikisininde bilimin içinde saygın ve müstesna yerleri vardır. Biri olmadan diğerini ifade edemeyiz. Yani birbirlerine muhtaçtırlar.

Fakat her ikisi de reelliğin veya reel olmanın kökenleri hakkında cevap veremezler. Bu da onların temel eksikleridir ve kendi içlerinde gideremezler. Bu sorunun bir kısmını mantık ve felsefe verebilse de onlarda bu konuda yetersizdir. Asıl bu konuya cevap veren din bilimlerinden Kelâm İlmi (İlm-i Kelâm) verebilir ki bununda kaynağı Kur’ân-ı Kerim yani doğrudan yaratıcının vahyi, sözleri, kelamı ve onun peygamberinin bizlere hitabıdır.

Buradaki silsile hem tümden gelim hem de tümevarım sonucu bulunabilinir. Herkesin aynı yöntemler sonucu bunların tamamına ulaşması veya herkesin aynı yöntemleri kullanması elbetteki beklenemez. Bu yüzden deliller her zaman en doğrudan, ispatlanarak yola çıkılması gerekir. İkinci sorun ise her insanın kısa ömründe asıl ulaşılması istenen hedeflere ulaşması gerekir ki buda her yöntem bu kısa zaman dilimi içinde aynı verimi ve sonuçları vermeyeceğinde yine en uygun sürede en verimli sonucun yani optimum sonucun kullanılması kaçınılmazdır. Üçüncü olarak verilerin doğrulanarak artması bir insanlık birikimi olacağından bunda ise ayrıntılar önem kazanmaktadır. İşte Dini bilimler daha çok ilk 2 yöntemi kullanırken Bilimsel yöntemler daha çok bu 3. yöntemi kullanmaktadırlar.

Her ikisini de kullanabilenler teorik, imani olanların yanında günlük olayları daha iyi kavrayabileceklerinden onların analizini, tahlilini, açıklamasını daha doğru yapabilmektedirler. Çünkü çoğu insan teoriden pratiği, formülden problemi çıkaramaz. Bu bir realitedir ve kaçınılmaz olarak devamlı tekrarlamaktadır. Bunları düşündüğümüzde her insanın bu ilimlerin hepsini belirli ölçülerde bilmesi gerekir.

Bunların eğitim ve öğretimini ise gerekli yaşlarda yapılması kaçınılmazdır. Yoksa sosyal felaketler kaçınılmaz olarak bizleri beklemektedir.

Özet/Abstract:

Ref. 1

Experimental observation of isolated large transverse energy electrons with associated missing energy at √s= 540 GeV

We report the results of two searches made on data recorded at the CERN SPS Proton-Antiproton Collider: one for isolated large-ET electrons, the other for large-ET neutrinos using the technique of missing transverse energy. Both searches converge to the same events, which have the signature of a two-body decay of a particle of mass ∼80 GeV/c2. The topology as well as the number of events fits well the hypothesis that they are produced by the proces pp, with W± →e±+ν; where W± is the Intermediate Vector Boson postulated by the unified theory of weak and electromagnetic inter- actions.

Ref. 5

The Nobel Prize in Physics 1984 was awarded jointly to Carlo Rubbia and Simon van der Meer “for their decisive contributions to the large project, which led to the discovery of the field particles W and Z, communicators of weak interaction”.

Fef. 6

Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC

The ATLAS Collaboration
(Submitted on 31 Jul 2012 (v1), last revised 31 Aug 2012 (this version, v2))
A search for the Standard Model Higgs boson in proton-proton collisions with the ATLAS detector at the LHC is presented. The datasets used correspond to integrated luminosities of approximately 4.8 fb^-1 collected at sqrt(s) = 7 TeV in 2011 and 5.8 fb^-1 at sqrt(s) = 8 TeV in 2012. Individual searches in the channels H->ZZ^(*)->llll, H->gamma gamma and H->WW->e nu mu nu in the 8 TeV data are combined with previously published results of searches for H->ZZ^(*), WW^(*), bbbar and tau^+tau^- in the 7 TeV data and results from improved analyses of the H->ZZ^(*)->llll and H->gamma gamma channels in the 7 TeV data. Clear evidence for the production of a neutral boson with a measured mass of 126.0 +/- 0.4(stat) +/- 0.4(sys) GeV is presented. This observation, which has a significance of 5.9 standard deviations, corresponding to a background fluctuation probability of 1.7×10^-9, is compatible with the production and decay of the Standard Model Higgs boson.

Ref. 7

Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC

The CMS Collaboration
(Submitted on 31 Jul 2012 (v1), last revised 28 Jan 2013 (this version, v2))
Results are presented from searches for the standard model Higgs boson in proton-proton collisions at sqrt(s) = 7 and 8 TeV in the Compact Muon Solenoid experiment at the LHC, using data samples corresponding to integrated luminosities of up to 5.1 inverse femtobarns at 7 TeV and 5.3 inverse femtobarns at 8 TeV. The search is performed in five decay modes: gamma gamma, ZZ, WW, tau tau, and b b-bar. An excess of events is observed above the expected background, with a local significance of 5.0 standard deviations, at a mass near 125 GeV, signalling the production of a new particle. The expected significance for a standard model Higgs boson of that mass is 5.8 standard deviations. The excess is most significant in the two decay modes with the best mass resolution, gamma gamma and ZZ; a fit to these signals gives a mass of 125.3 +/- 0.4 (stat.) +/- 0.5 (syst.) GeV. The decay to two photons indicates that the new particle is a boson with spin different from one.

 

Kaynaklar/References:

  1. http://www.sciencedirect.com/science/article/pii/0370269383911772
  2. http://home.web.cern.ch/about/updates/2013/02/w-boson-published-30-years-ago
  3. http://home.web.cern.ch/about/updates/2013/02/colliders-unite-linear-colliders-new-partnership
  4. http://home.web.cern.ch/about/updates/2013/01/carrying-weak-force-thirty-years-w-boson
  5. http://www.nobelprize.org/nobel_prizes/physics/laureates/1984/
  6. http://arxiv.org/pdf/1207.7214v2.pdf
  7. http://arxiv.org/pdf/1207.7235v2.pdf

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The search for the W boson

To find the W boson, CERN converted Europe’s largest accelerator, the Super Proton Synchrotron, into the world’s first proton-antiproton collider. The bold move paid off 

 
  • 19 February 1971

    Construction begins on the Super Proton Synchrotron (SPS)

    The Super Proton Synchrotron is designed to provide protons at 400 GeV for fixed-target experiments. Construction for this underground synchrotron begins on 19 February 1971.

     

  • 10 August 1972

    Simon van der Meer invents stochastic cooling

    Simon van der Meer at CERN writes a paper describing a technique to reduce the energy spread and angular divergence of a beam of charged particles. During this process of “stochastic cooling“, the particles are “compressed” into a finer beam with less energy spread and less angular divergence. By increasing the particle density to close to the required energy, this technique improved the beam quality and, among other things, brings the discovery of the W boson within reach.

  • 8 June 1976

    The SPS: From accelerator to collider

    At the International Neutrino Conference in Aachen, Germany, (8-12 June 1976) physicists Carlo Rubbia, Peter McIntyre and David Cline suggest modifying the Super Proton Synchrotron (SPS) from a one-beam accelerator into a two-beam collider. The two-beam configuration would collide a beam of protons with a beam of antiprotons, greatly increasing the available energy in comparison with a single beam colliding against a fixed target.

    Their paper on the subject, Producing Massive Neutral Intermediate Vector Bosons with Existing Accelerators is published in the conference proceedings the following year.

  • 17 June 1976

    SPS reaches its design energy of 400 GeV

    At 2.2 kilometres in diameter the Super Proton Synchrotron is Europe’s largest particle accelerator. Commissioning of the accelerator begins in mid-March 1976 using beams of protons. Then on 17 June 1976 the SPS accelerates a beam of protons at its design energy of 400 GeV for the first time. The machine is ready to supply beams to experiments.

  • 29 June 1978

    UA1 experiment approved

    CERN physicist Carlo Rubbia pulls together a team to put forward a proposal for an experiment code-named UA1, for “Underground Area 1“, since its location on the SPS requires a large cavern to be excavated. The team grows to involve some 130 physicists from 13 research centres – Aachen, Annecy LAPP, Birmingham, CERN, Helsinki, Queen Mary College London, Collège de France Paris, Riverside, Rome, Rutherford, Saclay, Vienna and Wisconsin. On 29 June 1978, the CERN Research Board accepts the proposal for a huge “general purpose” detector to record proton-antiproton collisions at 540 GeV.

  • 15 October 1979

    The weak side of the force

    Three physicists, Steven Weinberg, Abdus Salam and Sheldon Glashow, receive the Nobel prize in physics for proposing the electroweak theory. They believe that two of the four fundamental forces – the electromagnetic force and the weak force – are in fact different facets of the same force. Under high-energy conditions such as those in a particle accelerator, the two would merge into the electroweak force. But three hypothetical force-carrier particles described by the theory have yet to be confirmed in experiments: the W+, W- and Z0 bosons. These are heavy particles; so finding them would require an accelerator that could reach an unprecedented level of energy.

  • 3 July 1980

    First injection of protons into the Antiproton Accumulator

    Proton beams are injected and stored for the first time in the Antiproton Accumulator – a storage ring invented by CERN physicist Simon van der Meer where stochastic cooling produces intense antiproton beams. It took only two years from authorization of the machine to the announcement of first operation at the International Accelerator Conference at CERN, in July 1980. Within days, magnet polarities are reversed and antiprotons are injected and cooled.

  • 7 July 1981

    First acceleration of antiprotons in the SPS

    The Super Proton Synchrotron (SPS) accelerates its first pulse of antiprotons to 270 GeV. Two days later, with a proton beam orbiting in the opposite direction, there is the first evidence of proton-antiproton collisions. In August, the antiproton count reaches 109 and the UA1 calorimeter records some 4000 events. In October, the first visual evidence of the collisions is recorded in the streamer chambers of the UA5 detector (a precursor to UA2).

  • 10 July 1981

    First proton-antiproton collision in the SPS

    Carlo Rubbia delays his departure to the Lisbon High Energy Physics Conference by a day so that on 10 July 1981, he is able to announce that the UA1 detector has seen its first proton-antiproton collisions. UA2 takes its first data in December this same year.

  • 20 December 1982

    Director-General Schopper writes to Thatcher: Discovery imminent

    The first person outside CERN to be informed of the imminent discovery of the W boson is Margaret Thatcher, then Prime Minister of the United Kingdom, who paid a visit to CERN in August 1982. [See a video of the visit]. During her visit Thatcher asked the then Director-General of CERN Herwig Schopper to keep her updated on the progress of the search for the carriers of the weak force, the W and Z bosons.

    In a confidential letter dated 20 December 1982, Schopper wrote:

    “I am ever mindful of the promise I made on the occasion of your visit to CERN…that I would report to you immediately and directly on the day CERN obtained confirmed experimental evidence of the ‘intermediate boson’ (W+, W- and Z0) for which we are actively searching. …I am…pleased to inform you, in strict confidence, that the results recently obtained point to the imminence of such a discovery…”

  • 12 January 1983

    Signs of a W particle

    At the Topical Workshop on Proton-Antiproton Collider Physics in Rome from 12-14 January 1983, the first tentative evidence for observations of the W particle by the UA1 and UA2 collaborations is presented.

    Out of the several thousand million collisions recorded, a handful give signals, which could correspond to the production of a W in the high-energy collision and its subsequent decay into an electron (or positron if the W is positively charged) and a neutrino

  • 20 January 1983

    Reaching the goal

    The tension at CERN becomes electric, culminating in two seminars, from Carlo Rubbia (for UA1) on 20 January 1983 and Luigi Di Lella (for UA2) the following afternoon, both with the CERN auditorium packed to the roof. UA1 announces six candidate W events; UA2 announces four. The presentations are still tentative and qualified.

  • 25 January 1983

    The discovery of a W particle

    In a press conference on 25 January, CERN announces news of the discovery of the W boson to the world. The UA2 team reserves judgment at this stage but further analysis soon convinces them. From their results both teams estimate the boson’s mass at around 80 GeV, which is in excellent agreement with predictions from electroweak theory.

  • 17 October 1984

    Two CERN researchers, one Nobel prize

    The discovery of the W boson is so important that the two key physicists behind the discovery receive the Nobel prize in physics in 1984. The prize goes to Carlo Rubbia (pictured, left), instigator of the accelerator’s conversion and spokesperson of the UA1 experiment, and to Simon van der Meer (pictured, right), whose technology is vital to the collider’s operation.

    The discovery of the W boson is a significant achievement in physics that further validates the electroweak theory. It also helps to secure the decision to build CERN’s next big accelerator, the Large Electron Positron Collider, whose job is to mass-produce Z and W bosons for further studies.

  • 19 February 1971

    Construction begins on the Super Proton Synchrotron (SPS)

    The Super Proton Synchrotron is designed to provide protons at 400 GeV for fixed-target experiments. Construction for this underground synchrotron begins on 19 February 1971.

     

  • 10 August 1972

    Simon van der Meer invents stochastic cooling

    Simon van der Meer at CERN writes a paper describing a technique to reduce the energy spread and angular divergence of a beam of charged particles. During this process of “stochastic cooling“, the particles are “compressed” into a finer beam with less energy spread and less angular divergence. By increasing the particle density to close to the required energy, this technique improved the beam quality and, among other things, brings the discovery of the W boson within reach.

  • 8 June 1976

    The SPS: From accelerator to collider

    At the International Neutrino Conference in Aachen, Germany, (8-12 June 1976) physicists Carlo Rubbia, Peter McIntyre and David Cline suggest modifying the Super Proton Synchrotron (SPS) from a one-beam accelerator into a two-beam collider. The two-beam configuration would collide a beam of protons with a beam of antiprotons, greatly increasing the available energy in comparison with a single beam colliding against a fixed target.

    Their paper on the subject, Producing Massive Neutral Intermediate Vector Bosons with Existing Accelerators is published in the conference proceedings the following year.

  • 17 June 1976

    SPS reaches its design energy of 400 GeV

    At 2.2 kilometres in diameter the Super Proton Synchrotron is Europe’s largest particle accelerator. Commissioning of the accelerator begins in mid-March 1976 using beams of protons. Then on 17 June 1976 the SPS accelerates a beam of protons at its design energy of 400 GeV for the first time. The machine is ready to supply beams to experiments.

  • 29 June 1978

    UA1 experiment approved

    CERN physicist Carlo Rubbia pulls together a team to put forward a proposal for an experiment code-named UA1, for “Underground Area 1“, since its location on the SPS requires a large cavern to be excavated. The team grows to involve some 130 physicists from 13 research centres – Aachen, Annecy LAPP, Birmingham, CERN, Helsinki, Queen Mary College London, Collège de France Paris, Riverside, Rome, Rutherford, Saclay, Vienna and Wisconsin. On 29 June 1978, the CERN Research Board accepts the proposal for a huge “general purpose” detector to record proton-antiproton collisions at 540 GeV.

  • 15 October 1979

    The weak side of the force

    Three physicists, Steven Weinberg, Abdus Salam and Sheldon Glashow, receive the Nobel prize in physics for proposing the electroweak theory. They believe that two of the four fundamental forces – the electromagnetic force and the weak force – are in fact different facets of the same force. Under high-energy conditions such as those in a particle accelerator, the two would merge into the electroweak force. But three hypothetical force-carrier particles described by the theory have yet to be confirmed in experiments: the W+, W- and Z0 bosons. These are heavy particles; so finding them would require an accelerator that could reach an unprecedented level of energy.

  • 3 July 1980

    First injection of protons into the Antiproton Accumulator

    Proton beams are injected and stored for the first time in the Antiproton Accumulator – a storage ring invented by CERN physicist Simon van der Meer where stochastic cooling produces intense antiproton beams. It took only two years from authorization of the machine to the announcement of first operation at the International Accelerator Conference at CERN, in July 1980. Within days, magnet polarities are reversed and antiprotons are injected and cooled.

  • 7 July 1981

    First acceleration of antiprotons in the SPS

    The Super Proton Synchrotron (SPS) accelerates its first pulse of antiprotons to 270 GeV. Two days later, with a proton beam orbiting in the opposite direction, there is the first evidence of proton-antiproton collisions. In August, the antiproton count reaches 109 and the UA1 calorimeter records some 4000 events. In October, the first visual evidence of the collisions is recorded in the streamer chambers of the UA5 detector (a precursor to UA2).

  • 10 July 1981

    First proton-antiproton collision in the SPS

    Carlo Rubbia delays his departure to the Lisbon High Energy Physics Conference by a day so that on 10 July 1981, he is able to announce that the UA1 detector has seen its first proton-antiproton collisions. UA2 takes its first data in December this same year.

  • 20 December 1982

    Director-General Schopper writes to Thatcher: Discovery imminent

    The first person outside CERN to be informed of the imminent discovery of the W boson is Margaret Thatcher, then Prime Minister of the United Kingdom, who paid a visit to CERN in August 1982. [See a video of the visit]. During her visit Thatcher asked the then Director-General of CERN Herwig Schopper to keep her updated on the progress of the search for the carriers of the weak force, the W and Z bosons.

    In a confidential letter dated 20 December 1982, Schopper wrote:

    “I am ever mindful of the promise I made on the occasion of your visit to CERN…that I would report to you immediately and directly on the day CERN obtained confirmed experimental evidence of the ‘intermediate boson’ (W+, W- and Z0) for which we are actively searching. …I am…pleased to inform you, in strict confidence, that the results recently obtained point to the imminence of such a discovery…”

  • 12 January 1983

    Signs of a W particle

    At the Topical Workshop on Proton-Antiproton Collider Physics in Rome from 12-14 January 1983, the first tentative evidence for observations of the W particle by the UA1 and UA2 collaborations is presented.

    Out of the several thousand million collisions recorded, a handful give signals, which could correspond to the production of a W in the high-energy collision and its subsequent decay into an electron (or positron if the W is positively charged) and a neutrino

  • 20 January 1983

    Reaching the goal

    The tension at CERN becomes electric, culminating in two seminars, from Carlo Rubbia (for UA1) on 20 January 1983 and Luigi Di Lella (for UA2) the following afternoon, both with the CERN auditorium packed to the roof. UA1 announces six candidate W events; UA2 announces four. The presentations are still tentative and qualified.

  • 25 January 1983

    The discovery of a W particle

    In a press conference on 25 January, CERN announces news of the discovery of the W boson to the world. The UA2 team reserves judgment at this stage but further analysis soon convinces them. From their results both teams estimate the boson’s mass at around 80 GeV, which is in excellent agreement with predictions from electroweak theory.

  • 17 October 1984

    Two CERN researchers, one Nobel prize

    The discovery of the W boson is so important that the two key physicists behind the discovery receive the Nobel prize in physics in 1984. The prize goes to Carlo Rubbia (pictured, left), instigator of the accelerator’s conversion and spokesperson of the UA1 experiment, and to Simon van der Meer (pictured, right), whose technology is vital to the collider’s operation.

    The discovery of the W boson is a significant achievement in physics that further validates the electroweak theory. It also helps to secure the decision to build CERN’s next big accelerator, the Large Electron Positron Collider, whose job is to mass-produce Z and W bosons for further studies.

CER