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  • warning: Cannot modify header information - headers already sent by (output started at /websites/123reg/LinuxPackage21/ia/ns/am/iansample.com/public_html/site/includes/database.mysql.inc:128) in /websites/123reg/LinuxPackage21/ia/ns/am/iansample.com/public_html/site/includes/common.inc on line 141.
  • user warning: UPDATE command denied to user 'uiansam_485147_1'@'linweb12.atlas.pipex.net' for table 'truecache_filter' query: UPDATE truecache_filter SET data = '<p>To get to <a href=\"http://www.fnal.gov/\">Fermilab</a> from downtown Chicago, you find <a href=\"http://www.chicagotraveler.com/maps/chicago-beaches-map.htm\">Lake Michigan</a> and drive in the opposite direction. After about an hour on the freeway, the city shrinks to nothing in the rear-view mirror and you pick up an access road that turns into the 7,000 acre campus where the laboratory is based.</p>\n<p>The road cuts through a landscape of forests and lakes before arriving at one of my favourite sculptures. At first glance, it could be <a href=\"http://www.cretewest.com/PIX/talos.jpg\">Talos straddling the road in case the Argonauts pay a visit</a>, but this 21-ton metal monster was designed and built by Robert Wilson, a former cowboy and first director of the laboratory. From almost any angle, the sculpture looks ungainly and off-kilter <a href=\"http://www.fnal.gov/pub/presspass/vismedia/gallery/buildings.html\">(scroll down here)</a>, but lie on the road beneath it and look up. The sculpture&rsquo;s strained lines are hidden and a perfectly symmetrical form appears. It was meant to be that way. Wilson called the sculpture &ldquo;Broken Symmetry&rdquo;.</p>\n<p>The concept of symmetry breaking is fundamental in physics and central to the Higgs mechanism. The Higgs field breaks the symmetry between the electromagnetic force and the so-called weak force, the latter of which goes to work in certain radioactive processes and plays a vital role in keeping the sun shining. The field does this by giving mass to the weak force carrier particles, the W and Z bosons, while leaving the photon, which carries the electromagnetic force, massless and free to hurtle about at the speed of light. But that&rsquo;s another story.</p>\n<p>Fermilab is home to the Tevatron particle collider, an impressive old workhorse that lists among its successes the discovery of the top quark in 1995. The top quark is the heaviest known fundamental particle and weighs as much as a tungsten atom. If that doesn&rsquo;t sound much, bear in mind that a tungsten atom contains 74 protons, 110 neutrons and 74 electrons. It&rsquo;s the heaviest element used by living organisms.</p>\n<p>The Tevatron has been in the news again in recent weeks. <a href=\"http://www.science20.com/quantum_diaries_survivor/rumors_about_light_higgs\">A vague rumour</a> emerged on a physicist&rsquo;s blog that the Tevatron had found the Higgs boson. Some media outlets got a bit tangled up over the story, reporting one day that <a href=\"http://www.telegraph.co.uk/science/large-hadron-collider/7885997/Large-Hadron-Collider-rival-Tevatron-has-found-Higgs-boson-say-rumours.html\">the particle has been found</a>, and the next <a href=\"http://www.telegraph.co.uk/science/large-hadron-collider/7888012/Higgs-boson-discovery-rumours-false-say-Tevatron-scientists.html\">that it hadn&#39;t</a>. At the time, <a href=\"http://twitter.com/iansample/status/18368225595\">I bet Martin Rees&rsquo;s dog</a> that the Tevatron has not discovered the Higgs boson. That might seem an odd (not to say unethical) thing to bet, but <a href=\"http://iopscience.iop.org/0264-9381/25/22/229001\">it&rsquo;s not the first time</a> the poor creature&rsquo;s life has been wagered.</p>\n<p>There are two detector teams at the Tevatron, CDF and Dzero, and the teams are due to announce the combined results from their Higgs searches at 4pm Central European Time on Monday&nbsp; 26th July from the <a href=\"http://www.ichep2010.fr/\">ICHEP conference in Paris</a>. I&rsquo;ll post the results here at the same time, but for now, some background to explain why I don&rsquo;t think the Higgs has been found and why Lord Rees&#39;s dog is safe.</p>\n<p>In January, the Tevatron teams <a href=\"http://arxiv.org/abs/1001.4162\">published their last combined search for the Higgs particle</a>. The paper is pretty technical, but essentially it looks to see whether there is evidence for so-called Standard Model Higgs particles decaying into W bosons, however they are made in the first place in the machine. The searches rule out any Higgs boson (with 95% confidence) between a mass of 162 GeV and 166 GeV. A previous accelerator at Cern, the Large Electron Positron (LEP) collider, ruled out the possibility of the Higgs particle weighing less than 114.4 GeV. &nbsp;</p>\n<p>With six months or so more collisions under their belts, we might expect the Tevatron teams to have ruled out the existence of a Higgs particle over an even greater range of masses. That would be good news. It would narrow down the region where the Higgs must be hiding. We can&#39;t really expect them to have found the elusive beast. As I joked (very lamely) a week or so ago, physicists have waited so long to see the Higgs boson, or &quot;God particle&quot;, in their experiments, they might want to rename it <a href=\"http://twitter.com/iansample/status/18983671870\">the Godot particle</a>.</p>\n<p>&nbsp;<br />\nWhat is clear is that the Tevatron and its detector teams are working well and making solid progress in the hunt for the Higgs particle. Officially, the machine is due to close at the end of 2011, but a proposal to run for a few years longer is under consideration. With the <a href=\"http://lhc.web.cern.ch/lhc/\">Large Hadron Collider at Cern</a> having little chance of finding the Higgs boson before it begins high energy runs at the end of 2012, there is surely a strong argument to keep the Tevatron in the race.<br />\n&nbsp;</p>\n', created = 1566235512, expire = 1566321912, headers = '', serialized = 0 WHERE cid = '1:7e944343779246f601f05d899a531834' in /websites/123reg/LinuxPackage21/ia/ns/am/iansample.com/public_html/site/includes/cache.inc on line 109.
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Waiting for the Godot particle

To get to Fermilab from downtown Chicago, you find Lake Michigan and drive in the opposite direction. After about an hour on the freeway, the city shrinks to nothing in the rear-view mirror and you pick up an access road that turns into the 7,000 acre campus where the laboratory is based.

The road cuts through a landscape of forests and lakes before arriving at one of my favourite sculptures. At first glance, it could be Talos straddling the road in case the Argonauts pay a visit, but this 21-ton metal monster was designed and built by Robert Wilson, a former cowboy and first director of the laboratory. From almost any angle, the sculpture looks ungainly and off-kilter (scroll down here), but lie on the road beneath it and look up. The sculpture’s strained lines are hidden and a perfectly symmetrical form appears. It was meant to be that way. Wilson called the sculpture “Broken Symmetry”.

The concept of symmetry breaking is fundamental in physics and central to the Higgs mechanism. The Higgs field breaks the symmetry between the electromagnetic force and the so-called weak force, the latter of which goes to work in certain radioactive processes and plays a vital role in keeping the sun shining. The field does this by giving mass to the weak force carrier particles, the W and Z bosons, while leaving the photon, which carries the electromagnetic force, massless and free to hurtle about at the speed of light. But that’s another story.

Fermilab is home to the Tevatron particle collider, an impressive old workhorse that lists among its successes the discovery of the top quark in 1995. The top quark is the heaviest known fundamental particle and weighs as much as a tungsten atom. If that doesn’t sound much, bear in mind that a tungsten atom contains 74 protons, 110 neutrons and 74 electrons. It’s the heaviest element used by living organisms.

The Tevatron has been in the news again in recent weeks. A vague rumour emerged on a physicist’s blog that the Tevatron had found the Higgs boson. Some media outlets got a bit tangled up over the story, reporting one day that the particle has been found, and the next that it hadn't. At the time, I bet Martin Rees’s dog that the Tevatron has not discovered the Higgs boson. That might seem an odd (not to say unethical) thing to bet, but it’s not the first time the poor creature’s life has been wagered.

There are two detector teams at the Tevatron, CDF and Dzero, and the teams are due to announce the combined results from their Higgs searches at 4pm Central European Time on Monday  26th July from the ICHEP conference in Paris. I’ll post the results here at the same time, but for now, some background to explain why I don’t think the Higgs has been found and why Lord Rees's dog is safe.

In January, the Tevatron teams published their last combined search for the Higgs particle. The paper is pretty technical, but essentially it looks to see whether there is evidence for so-called Standard Model Higgs particles decaying into W bosons, however they are made in the first place in the machine. The searches rule out any Higgs boson (with 95% confidence) between a mass of 162 GeV and 166 GeV. A previous accelerator at Cern, the Large Electron Positron (LEP) collider, ruled out the possibility of the Higgs particle weighing less than 114.4 GeV.  

With six months or so more collisions under their belts, we might expect the Tevatron teams to have ruled out the existence of a Higgs particle over an even greater range of masses. That would be good news. It would narrow down the region where the Higgs must be hiding. We can't really expect them to have found the elusive beast. As I joked (very lamely) a week or so ago, physicists have waited so long to see the Higgs boson, or "God particle", in their experiments, they might want to rename it the Godot particle.

 
What is clear is that the Tevatron and its detector teams are working well and making solid progress in the hunt for the Higgs particle. Officially, the machine is due to close at the end of 2011, but a proposal to run for a few years longer is under consideration. With the Large Hadron Collider at Cern having little chance of finding the Higgs boson before it begins high energy runs at the end of 2012, there is surely a strong argument to keep the Tevatron in the race.
 

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