[Deepwater6]

http://www.bbc.co.uk...onment-16070460

A few things to look forward to this year... Hope everyone has a nice holiday.

[phision]

Deepwater6, on 01 January 2012 - 12:27 PM, said:

http://www.bbc.co.uk...onment-16070460

Read the above link and found: "20 inverse femtobarns of data", can anyone enlighten me to what the BBC was trying to convey here? Is a Barn not a unit of area?

[CraigD]

phision, on 08 January 2012 - 07:04 PM, said:

Read the above link and found: "20 inverse femtobarns of data", can anyone enlighten me to what the BBC was trying to convey here? Is a Barn not a unit of area?

The barn is a unit of area, 10^-28 m², so a femtobarn is 10^-43 m².

An "inverse barn" or "inverse femtobarn" is a bit of a misnomer, as it doesn't mean 10²⁸ or 10⁴³ m^-2, but 10²⁸ or 10⁴³ events/m². Thus, it's a unit of the product of the "brightness" of particle physics sources, the efficiency of the detection apparatus, and the duration of the experiments.

All said, I think events per unit area is an awkward, confusing unit compared to simply a count of events, so not as useful to the non-specialist.

[phision]

CraigD, on 08 January 2012 - 11:00 PM, said:

All said, I think events per unit area is an awkward, confusing unit compared to simply a count of events, so not as useful to the non-specialist.

Thank you CraigD. I agree, it is awkward!

I also believe the author of the article didn't understand the unit as it should have been described as a data set relating to an instantaneous luminosity if associated with a time scale(ie fb⁻¹s⁻¹), to describe a productive rate, or a data set relating to an integrated luminosity, to descibe a total productivity. It may only have been a grammatical error, but one the renders the description as useless to anyone who does not use this terminology in the abbrivated language that people who use this unit every-day must do!

[maddog]

phision, on 08 January 2012 - 07:04 PM, said:

Read the above link and found: "20 inverse femtobarns of data", can anyone enlighten me to what the BBC was trying to convey here? Is a Barn not a unit of area?

Uhh, Yeah I see where this could sound a bit physhy (excuse my pun).

I would interpret the phrase "20 inverse femtobarns of data" as "20 / femtobarns of data" or
data = 20/fb (i.e. 20 event per femtobarn). You are right this does sound like a luminosity like value
(as events per unit area).

Definition of fb = femtobarn is as CraigD already said.

maddog