### Re: Current Events Discussion

Posted:

**Tue Jul 13, 2010 9:40 pm**Does anyone know the buckets involved with the 12b_8_8_8? I have found information on 13b_8_8_8 but not the 12b.

Thanks

Thanks

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Posted: **Tue Jul 13, 2010 9:40 pm**

Does anyone know the buckets involved with the 12b_8_8_8? I have found information on 13b_8_8_8 but not the 12b.

Thanks

Thanks

Posted: **Tue Jul 13, 2010 10:36 pm**

Found the bucket numbers on the e-log; hope I did not put anyone to any trouble

Thanks

Thanks

Posted: **Tue Jul 13, 2010 11:38 pm**

Posted: **Wed Jul 14, 2010 12:04 am**

Thanks, however I had found that site a day or so ago and the 12b was not there; it has been added since I last visited the site.

Posted: **Wed Jul 14, 2010 5:27 am**

does anyone know if the events in the ATLAS live display, are minimun bias events or the ones that pass though the high level triggers.

Posted: **Wed Jul 14, 2010 3:28 pm**

Today's run was the best yet with about 15 hours of stable beams and luminosities above 1.0 for most of the run. No sign if the sharp losses seen on previous runs. integrated luminosity was about 50 inverse nanobarns taking accumulated total to around 200 inverse nanobarns. LHC is starting to behave itself. Run was finally ended by an electrical network glitch.

Posted: **Wed Jul 14, 2010 5:19 pm**

i like this

Posted: **Thu Jul 15, 2010 3:30 pm**

They are currently hunting the Hump by switching off the "GSM" in the tunnel.

I wonder if this is the same GSM that we use for wireless communication?

ikarus177

I wonder if this is the same GSM that we use for wireless communication?

ikarus177

Posted: **Thu Jul 15, 2010 3:33 pm**

I'm confused...

The last post said...

What are the rules for calculating with inverse xxbarns?

The last post said...

But I read an article that said...taking accumulated total to around 200 inverse nanobarns

Femto is smaller than nano.The goal in the next year is to get to one inverse femtobarn

What are the rules for calculating with inverse xxbarns?

Posted: **Thu Jul 15, 2010 3:46 pm**

I think the key word here is 'inverse', why they seem to do this backwards I'm not sure, some scientific reason no doubt, but personally I think a Gigabarn sounds betterMpVpRb wrote:I'm confused...

The last post said...

But I read an article that said...taking accumulated total to around 200 inverse nanobarns

Femto is smaller than nano.The goal in the next year is to get to one inverse femtobarn

What are the rules for calculating with inverse xxbarns?

Posted: **Thu Jul 15, 2010 3:50 pm**

femtobarn is smaller than nanobarn, so inverse femtobarn is bigger than inverse nanobarn. It is terminology designed to confuse. They should just call an inverse barn a narb so that they can talk about Meganarbs, Giganarbs , Teranarbs etc.

So now they have about 240 Giganarbs. They are aiming for 100 Teranarbs this year and a Petanarb by the end of 2012. That make more sense?

So now they have about 240 Giganarbs. They are aiming for 100 Teranarbs this year and a Petanarb by the end of 2012. That make more sense?

Posted: **Thu Jul 15, 2010 6:24 pm**

Yes but isn't the aim to produce one inverse femtobarn at 14 TeV centre of mass ? Since the machine is operating at only 7 TeV presumably this won't be adding to this total.PhilG wrote:femtobarn is smaller than nanobarn, so inverse femtobarn is bigger than inverse nanobarn. It is terminology designed to confuse. They should just call an inverse barn a narb so that they can talk about Meganarbs, Giganarbs , Teranarbs etc.

So now they have about 240 Giganarbs. They are aiming for 100 Teranarbs this year and a Petanarb by the end of 2012. That make more sense?

Posted: **Thu Jul 15, 2010 7:37 pm**

Let's make an example in better understandable scales (but as a result, waaaay out of the real scale). Imagine the beam cross-section is one square meter. So far they got 10 collisions per square decimeter (10 inverse dm2s), which means one thousand collisions total. They aim for one collision per square milimeter (1 inverse mm2), which is smaller number and smaller area but in fact it means much more - one million of collisions total.MpVpRb wrote:Femto is smaller than nano.The goal in the next year is to get to one inverse femtobarn

What are the rules for calculating with inverse xxbarns?

It's similar with nano- and femtobarns as they are also units of beam cross-section area. They are using these tiny area units to illustrate how well the target (proton in opposite direction) has been probed. Inverse femtobarn is way smaller than proton cross-section so it gives good chance that all possible scattering angles have been sufficiently probed.

Posted: **Thu Jul 15, 2010 9:24 pm**

The rough plan is one inverse femtobarn at 7TeV by end of 2011 and 60 inverse femtobarn at 14Tev by end of 2016.DCWhitworth wrote:Yes but isn't the aim to produce one inverse femtobarn at 14 TeV centre of mass ? Since the machine is operating at only 7 TeV presumably this won't be adding to this total.

See https://indico.desy.de/getFile.py/acces ... onfId=1964

Posted: **Fri Jul 16, 2010 6:16 pm**

So...I'm still confused about inverse xxbarns.

If smaller numbers mean more data, why do the numbers increase over time on these plots?

http://lpc.web.cern.ch/lpc/lumiplots.htm

If smaller numbers mean more data, why do the numbers increase over time on these plots?

http://lpc.web.cern.ch/lpc/lumiplots.htm