Larry Desjardin writes:
I had the fortune to visit CERN (European Council for Nuclear Research) earlier this month. Located on the Franco-Swiss border, CERN is home to the most powerful particle accelerator mankind has ever built, the Large Hadron Collider, otherwise known as the LHC. Here, bunches of approximately 100 billion protons each are accelerated in opposing directions around a 27-kilometer ring to collide at needle-point accuracy.
Fellow blogger, Ransom Stephens, published an excellent 8-part series last year about the LHC and the Higgs Boson discovery, which you can read here. I highly recommend it. I will relate my own first-hand experience in today’s post, and the impressive engineering required to create the experiments. Though I lived near Geneva for nearly four years, this was the first time I ever visited the facility.
Journey to the center of the universe – [Link]
Development in CERN never stops. Scientists from all over the world are working to improve every aspect of this giant experiment. That’s what happens on ALICE project in an effort to improve the current Inner Tracking System (ITS) and overcome difficulties encountered on the current detector technologies.
ITS Upgrade Project is responsible for the development of new detectors that will upgrade the ALICE project. Two new technologies are discussed to move the detectors on a new level. “Hybrid silicon pixel detectors” and ” monolithic silicon pixel detectors” are the basic concepts. There are already prototypes evaluated for the new silicon detectors.
Within the WG3 prototypes for both pixel technologies have been realized in the course of the past year. One of the main challenges is clearly the limitation in allowed material budget. This is necessary in order to improve the impact parameter resolution at low pT by about a factor of 3. A total of 0.3% X0 per layer is about a factor 3 less than used in the present ALICE silicon pixel detector, which is already the pixel detector with the lowest material budget of all LHC detectors. The thickness requirements for each component are therefore stringent. Silicon thicknesses of 50 µm in case of monolithic detectors or 100+50 µm in case of hybrid pixel detectors require special developments, which have been pursued within the WG3 community.
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ALICE Inner Tracking System (ITS) is upgrating to new detector technologies – [Link]
[1112.5154] Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS – [via]
The chi_b(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb^-1, these states are reconstructed through their radiative decays to Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new structure centered at a mass of 10.539+/-0.004 (stat.)+/-0.008 (syst.) GeV is also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes. This is interpreted as the chi_b(3P) system.
New particle indentified at LHC – The Chi-b 3P boson – [Link]