PR20.10 – 08.11.2010

CERN completes transition to lead-ion running at the LHC

Geneva, 8 November 2010. Four days is all it took for the LHC operations team at CERN* to complete the transition from protons to lead ions in the LHC. After extracting the final proton beam of 2010 on 4 November, commissioning the lead-ion beam was underway by early afternoon. First collisions were recorded at 00:30 CET on 7 November, and stable running conditions marked the start of physics with heavy ions at 11:20 CET today.

“The speed of the transition to lead ions is a sign of the maturity of the LHC,” said CERN Director General Rolf Heuer. “The machine is running like clockwork after just a few months of routine operation.”

Operating the LHC with lead ions – lead atoms stripped of electrons – is completely different from operating the machine with protons. From the source to collisions, operational parameters have to be re-established for the new type of beam. For lead-ions, as for protons before them, the procedure started with threading a single beam round the ring in one direction and steadily increasing the number of laps before repeating the process for the other beam. Once circulating beams had been established they could be accelerated to the full energy of 287 TeV per beam. This energy is much higher than for proton beams because lead ions contain 82 protons. Another period of careful adjustment was needed before lining the beams up for collision, and then finally declaring that nominal data taking conditions, known at CERN as stable beams, had been established. The three experiments recording data with lead ions, ALICE, ATLAS and CMS can now look forward to continuous lead-ion running until CERN’s winter technical stop begins on 6 December.

“It’s been very impressive to see how well the LHC has adapted to lead ions,” said Jurgen Schukraft, spokesperson of the ALICE experiment. “The ALICE detector has been optimised to record the large number of tracks that emerge from ion collisions and has handled the first collisions very well, so we are all set to explore this new opportunity at LHC.”

“After a very successful proton run, we’re very excited to be moving to this new phase of LHC operation,” said ATLAS spokesperson Fabiola Gianotti. “The ATLAS detector has recorded first spectacular heavy-ion events, and we are eager to study them in detail.”

“We designed CMS as a multi-purpose detector,” said Guido Tonelli, the collaboration’s spokesperson,  “and it’s very rewarding to see how well it’s adapting to this new kind of collision. Having data collected by the same detector in proton-proton and heavy-ion modes is a powerful tool to look for unambiguous signatures of new states of matter.”

Lead-ion running opens up an entirely new avenue of exploration for the LHC programme, probing matter as it would have been in the first instants of the Universe’s existence. One of the main objectives for lead-ion running is to produce tiny quantities of such matter, which is known as quark-gluon plasma, and to study its evolution into the kind of matter that makes up the Universe today. This exploration will shed further light on the properties of the strong interaction, which binds the particles called quarks, into bigger objects, such as protons and neutrons.

Following the winter technical stop, operation of the collider will start again with protons in February and physics runs will continue through 2011.

CERN press office

PR19.10 – 04.11.2010

 The LHC enters a new phase
 Geneva, 4 November 2010.  Proton running for 2010 in the LHC at CERN[1] came to a successful conclusion today at 08:00 CET. Since the end of March, when the first collisions occurred at a total energy of 7 TeV, the machine and experiment teams have achieved all of their objectives for the first year of proton physics at this record energy and new ground has been explored. For the rest of the year the LHC is moving to a different phase of operation, in which lead ions will be accelerated and brought into collision in the machine for the first time.

A major target for 2010 was to reach a luminosity – a measure of the collision rate – of 10³² per square centimetre per second. This was achieved on 13 October, with two weeks to spare. Before proton running came to an end, the machine had reached twice this figure, allowing experiments to double the amount of data collected in the space of only a few days.

“This shows that the objective we set ourselves for this year was realistic, but tough, and it’s very gratifying to see it achieved in such fine style,” said Rolf Heuer, CERN’s Director General. “It’s a testimony to the excellent design of the machine as well as to the hard work that has gone in to making it succeed. It bodes well for our targets for 2011.” The main goal for 2011 is for the experiments to collect enough data – an amount known by the physicists as one inverse femtobarn – to make significant advances across a broad frontier of physics.

The LHC experiments have already entered new territory with their first measurements at a total energy of 7 TeV. The results so far have included the validation of aspects of the Standard Model of particles and forces at these new high energies; the first observations of the top quark in proton-proton collisions; limits set on the production of certain new particles, for example “excited” quarks; and hints of effects in proton-proton collisions that may be linked to previous observations in the collisions of heavy ions. 

“The experiments are already providing an exciting glimpse of the new frontier”, said Sergio Bertolucci, Director for Research and Computing. “This rapid delivery of the first physics measurements at 7 TeV is a direct result of the excellent performance of the detectors, the high efficiency of the data collection and the swift distribution of data via the Worldwide LHC Computing Grid for analysis at centres across the globe.”

The Worldwide LHC Computing Grid (WLCG) combines the computing power of more than 140 independent computer centres in 34 countries and supports the LHC experiments. It handles more than a million computing jobs a day with hundreds of physicists performing data analysis. Data has been transferred at impressive rates, witnessing peaks of 10 gigabytes per second, the equivalent of two full DVDs of data a second.

The change to running with lead ions – lead atoms stripped of electrons – opens up an entirely new avenue of exploration for the LHC programme, probing matter as it would have been in the first instants of the Universe’s existence. One of the main objectives for lead-ion running is to produce tiny quantities of such matter, which is known as quark-gluon plasma, and to study its evolution into the kind of matter that makes up the Universe today. This exploration will shed further light on the properties of the strong interaction, which binds the particles called quarks, into bigger objects, such as protons and neutrons.

“Heavy-ion collisions provide a unique micro-laboratory for studying very hot, dense matter,” said Jurgen Schukraft, spokesperson of the ALICE experiment, which is optimized to study lead-ion collisions at the LHC. “At the LHC we’ll be continuing a journey that began for CERN in 1994, which is certain to provide a new window on the fundamental behaviour of matter and in particular the role of the strong interaction.”

The WLCG faces a new challenge with lead-ion collisions, as the flow of data will be significantly greater than for proton-proton collisions.  Recent tests have demonstrated the readiness of the data storage system at CERN to accept data at more than three times the rate achieved for proton-proton collisions, and more than double the rate originally anticipated for heavy ions.

The LHC will run with lead ions until 6 December, before a technical stop for maintenance. Operation of the collider will start again with protons in February and physics runs will continue through 2011.

CERN press office

+41 22 767 34 32/21 41

Geneva 30 March 2010. 7 TeV beams collided in the LHC at 13:06 CEST, marking the start of the LHC research programme. Particle physicists around the world are looking forward to a potentially rich harvest of new physics as the LHC begins its first long run at an energy three and a half times higher than previously achieved at a particle accelerator.

“It’s a great day to be a particle physicist,” said CERN Director General Rolf Heuer. “A lot of people have waited a long time for this moment, but their patience and dedication is starting to pay dividends.”

“With these record-shattering collision energies, the LHC experiments are propelled into a vast region to explore, and the hunt begins for dark matter, new forces, new dimensions and the Higgs boson,” said ATLAS collaboration spokesperson, Fabiola Gianotti. “The fact that the experiments have published papers already on the basis of last year’s data bodes very well for this first physics run.”

“We’ve all been impressed with the way the LHC has performed so far,” said Guido Tonelli, spokesperson of the CMS experiment, “and it’s particularly gratifying to see how well our particle detectors are working while our physics teams worldwide are already analysing data. We’ll address soon some of the major puzzles of modern physics like the origin of mass, the grand unification of forces and the presence of abundant dark matter in the universe. I expect very exciting times in front of us.”

“This is the moment we have been waiting and preparing for”, said ALICE spokesperson Jürgen Schukraft. “We’re very much looking forward to the results from proton collisions, and later this year from lead-ion collisions, to give us new insights into the nature of the strong interaction and the evolution of matter in the early Universe.”

“LHCb is ready for physics,” said the experiment’s spokesperson Andrei Golutvin, “we have a great research programme ahead of us exploring the nature of matter-antimatter asymmetry more profoundly than has ever been done before.”

CERN will run the LHC for 18-24 months with the objective of delivering enough data to the experiments to make significant advances across a wide range of physics channels. As soon as they have  ”re-discovered” the known Standard Model particles, a necessary precursor to looking for new physics, the LHC experiments will start the systematic search for the Higgs boson. With the amount of data expected, called one inverse femtobarn by physicists, the combined analysis of ATLAS and CMS will be able to explore a wide mass range, and there’s even a chance of discovery if the Higgs has a mass near 160 GeV. If it’s much lighter or very heavy, it will be harder to find in this first LHC run.

For supersymmetry, ATLAS and CMS will each have enough data to double today’s sensitivity to certain new discoveries. Experiments today are sensitive to some supersymmetric particles with masses up to 400 GeV. An inverse femtobarn at the LHC pushes the discovery range up to 800 GeV.

“The LHC has a real chance over the next two years of discovering supersymmetric particles,” explained Heuer, “and possibly giving insights into the composition of about a quarter of the Universe.”

Even at the more exotic end of the LHC’s potential discovery spectrum, this LHC run will extend the current reach by a factor of two. LHC experiments will be sensitive to new massive particles indicating the presence of extra dimensions up to masses of 2 TeV, where today’s reach is around 1 TeV.

“Over 2000 graduate students are eagerly awaiting data from the LHC experiments,” said Heuer.  “They’re a privileged bunch, set to produce the first theses at the new high-energy frontier.”

Following this run, the LHC will shutdown for routine maintenance, and to complete the repairs and consolidation work needed to reach the LHC’s design energy of 14 TeV following the incident of 19 September 2008. Traditionally, CERN has operated its accelerators on an annual cycle, running for seven to eight months with a four to five month shutdown each year. Being a cryogenic machine operating at very low temperature, the LHC takes about a month to bring up to room temperature and another month to cool down. A four-month shutdown as part of an annual cycle no longer makes sense for such a machine, so CERN has decided to move to a longer cycle with longer periods of operation accompanied by longer shutdown periods when needed.

“Two years of continuous running is a tall order both for the LHC operators and the experiments, but it will be well worth the effort,” said Heuer. “By starting with a long run and concentrating preparations for 14 TeV collisions into a single shutdown, we’re increasing the overall running time over the next three years, making up for lost time and giving the experiments the chance to make their mark.”

LHC sets new record – accelerates beam to 3.5 TeV

Geneva, 19 March 2010. At just after 5:20 this morning, two 3.5 TeV proton beams successfully circulated in the Large Hadron Collider for the first time. This is the highest energy yet achieved in a particle accelerator, and an important step on the way to the start of the LHC research programme. The first attempt to collide beams at 7 TeV (3.5 TeV per beam) will follow on a date to be announced in the near future.

“Getting the beams to 3.5 TeV is testimony to the soundness of the LHC’s overall design, and the improvements we’ve made since the breakdown in September 2008,” explained CERN*’s Director for Accelerators and Technology, Steve Myers. “And it’s a great credit to the patience and dedication of the LHC team.”

The current LHC run began on 20 November 2009, with the first circulating beam at 0.45 TeV.  Milestones were quick to follow, with twin circulating beams established by 23 November and a world record beam energy of 1.18 TeV being set on 30 November. By the time the LHC switched off for 2009 on 16 December, another record had been set with collisions recorded at 2.36 TeV and significant quantities of data recorded. Over the 2009 part of the run, each of the LHC’s four major experiments, ALICE, ATLAS, CMS and LHCb recorded over a million particle collisions, which were distributed smoothly for analysis around the world on the LHC computing grid. The first physics papers were soon to follow.

After the 2.36 TeV collisions, a technical stop ensued at the beginning of 2010, during which the machine was prepared for higher-energy running. Higher energy collisions require higher electrical currents in the LHC magnet circuits. This places more exacting demands on the new machine protection systems, which have now been readied for the task.

Once 7 TeV collisions have been established, the plan is to run continuously for a period of 18-24 months, with a short technical stop at the end of 2010. This will bring enough data across all the potential discovery areas to firmly establish the LHC as the world’s foremost facility for high-energy particle physics.

Vi husker vel alle at det i media høsten 2009 med store overskrifter ble varslet om nært forestående dommedag og /eller konstruksjon av sorte hull som ville sluke jorden.
Vel, jorden består fremdeles, så det ville være interessant å få et innblikk i hva CERN (European Organization for Nuclear Research) egentlig gjør, og har gjort…

DEL 1. Historikk / Oversikt

CERN ble opprettet i 1954 av 12 medlemsland (deriblant Norge). Senteret ligger hovedsakelig i Sveits (ved Geneve), men deler av anlegget ligger også over grensen til Frankrike. I dag består CERN av 20 medlemsland.
CERN er pr. definisjon ”..en organisasjon for forskning på partikkelfysikk, kjernefysikk og kjernekjemi.”
CERN beskriver hensikten med organisasjonen selv, ved å si at de prøver å gi svar på følgende spørsmål:
- Hva består universet av?
- Hvordan har det utviklet seg?

Interessant er å merke seg at det i deres statutter presiseres at arbeidet de gjør ikke skal gjøres for fremme av militære behov, samt at resultater av deres forskning skal gjøres allmenn kjent.

CERN utforsker materien ved hjelp av partikkelakseleratorer. Partikkelstråler skal akselereres og kollidere partikler (protoner eller ioner), mot hverandre eller mot andre mål. Hastighet som skal oppnås er mer enn 99,9 % av lysets hastighet. På denne måten skaper man energikonsentrasjoner som er like høye som i universets første øyeblikk, altså et slags mini ”big bang”. Energien utløst ved kollisjonene (800 millioner partikkelkollisjoner hvert sekund) vil konverteres til materie, altså nye partikler. Dette utledet fra E =mc2 (Energi = konsentrert masse).
Mest kjent fra CERN i denne forbindelse er LHC (Lage Hadron Collider), eller også kjent som ”tidenes kraftigste maskin”.

LHC er konstruert i en 27 km. sirkulær tunnel. (se bildet over.) For å få ledet strålene som skal kollidere mot hverandre så benytter man sterke elektriske og magnetiske felt som gradvis øker hastighet og energien til protonene i LHC før de endelig kolliderer.
Flere meget avanserte detektorer registrerer hva som skjer når partiklene støter sammen, og måler forskjellige egenskaper ved de nye partiklene som oppstår i kollisjonen.

Grunnlaget for store skrekkoppslag verden over, er at man ikke helt vet hva som vil oppstå rett etter kollisjonen. Forskning tyder på at det produseres partikler i ”par”: ”Materie” og ”Antimaterie”. Energi som utløses ved kollisjonen vil kunne danne nye slike ”par” som igjen umiddelbart vil utligne hverandre og bli konvertert til energi.

Påstander har blitt fremsatt om at det vil bli produsert: Sorte hull som vil sluke jorden, ukjente ”Strangelets” som vil medføre en kjedereaksjon med alt stoff på jorden, partikler med kun en magnetisk pol, som vil bryte ned alle protoner på jorden, eller en ”vakuumboble” som gjør at hele universet vil komme i en tilstand med lavere energi.

Det meste av dette tilbakevises bl.a. med henvisning til den naturlige kosmiske strålingen som hele tiden bombarderer bl.a. jordkloden med partikler. Det stadfestes at kollisjoner som er kraftigere enn det LHC klarer å produsere, har skjedd utallige ganger fra kosmisk bakgrunnsstråling av naturlige årsaker, uten at universet eller jorden har gått til grunne. (Ref. ”kosmisk bakgrunnsstråling” er resultatet av utligning etter kollisjoner umiddelbart etter ”the big bang”.)

WLCG
LHC produserer enorme mengder data som må analyseres, og i denne forbindelse leder CERN et arbeid for å utnytte store mengder regnekapasitet gjennom et verdensomspennende computernettverk, også kalt ”GRID”, eller WLCG (Worldwide LHC Computing Grid)
LHC vil produsere utrolige 15 Petabytes (15 millioner Gb) med data årlig. WLCG har til hensikt å konstruere og vedlikeholde lagringsplass og infrastruktur slik at hele denne datamengden kan analyseres og bearbeides. (Hvis all data skulle blitt lagret på CDèr ville dette tilsvart en 20 km høy søyle)

WLCG kombinerer i dag kapasitet fra over 100.000 prosessorer i 34 land. 8000 forskere kan som en følge av dette få tilnærmet umiddelbar tilgang til LHC`s data, og prosessorkraft til å bearbeide dataene.

Et interessant historisk tilbakeblikk: World Wide Web, WWW, ble oppfunnet ved CERN i 1990 av Sir Tim Berners Lee og Robert Cailliau for å lette kommunikasjonen mellom partikkelfysikere rundt om i verden. (Ikke å forveksle med Internett, som ble født i løpet av  60 årene i Amerika, ref. ARPANET). 

Samfunnet har nytt godt av forskning fra CERN gjennom tidene, man kan nevne: Partikkeldetektorer utviklet ved CERN som benyttes innen medisinen til medisinsk avbildning og diagnoser, generelt også avansement innen områder som kryogenikk, superleding, vakuumteknikk, mikroelektronikk, overflateteknikk m.m.

Status ved LHC:

De første strålene sirkulerte i LHC 20.11. 2009, og de første kollisjonene med 900 GeV (450 GeV pr. stråle) fulgte 23.11.

Ny verdensrekord ble satt 29 nov. da stråleenergien ble akselerert til 1,18 TeV.

Etter en teknisk stopp, ble eksperimentet gjenopptatt 28.02.2010

Dette er forskjellige ”milestones” på vei mot endelige eksperimenter med LHC som begynner ved 14 TeV (7 TeV) pr. stråle. Dette vil skje allerede i løpet av mars 2010 hvis alt går etter planen.

(1 TeV tilsvarer energien til en mygg som flyr. Et proton er en billion ganger mindre enn en mygg. En annen sammenligning: Hver stråle vil ha en energi som tilsvarer et hurtigtog som kjører i en fart på 200 km/t)

På forsiden av hjemmesiden til SCRIBO vil det bli opprettet en kolonne med overskrift ”CERN” som automatisk vil hente de siste pressenyheter fra CERN

Påfølgende artikler vil hhv. omhandle LHC og WLCG

Kilder: Diverse pressemateriale fra CERN, Wikipedia.