hmm.. lets see... _ _
25 ns. . . . . new settings !! . . . . . . .
(what does 25ns mean if you are injecting one bunch ? just a doubled RF ?)
latest-news @ 12:04 - 288 b stable with high chromaticity
whew ....
by chromaticity are they refering to spread in kinetic energy in the bunch?
2) ATS !
there must be dozens, if not hundreds of random physics anagrams that match.
I go on record with a random guess of Advanced Tracking System.
Any praise ? _ _ _ _ . . . . . . or is it only scorn? _ _
( Although, come to think of it, an Anti-Tachyon Synchronizer might be handy. )
3) I was unable to watch the entire ultralow beta* squeeze
I gather that the target was beta*=0.10m at IP1 and IP5 and the OP Vistars view at LHC configuration seemed to indicate that an eight hour squeeze was unsuccessful. Beta* minned out at 0.55m. Although increased squeeze occurred IP2 (5.33->4.92->4.16) and at IP8 (3.14->3.07->2.81) the configuration page showed no change at IP1 and IP5.
After they lost beam1 (@ ~2:50) the operator commented:
@ 2:59:42 beta* = 14 cm Only for beam2 . . .
@ 3:13:40 ATS MD 10 cm beta* optics measurement
Does anyone know how quickly they were able to achieve beta*=0.55m ?
Any comments on why LHC Configuration page never showed the beta* values that the operator quoted ?
Does anyone have insight into the filling scheme nomenclature ?
_wp ?
_nLR ?
EXCELSIOR !
Why So QUIET ??? Machine Development !!!!!
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- chriwi
- LHCPortal Guru
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- Contact:
Re: Why So QUIET ??? Machine Development !!!!!
Hi gilgamorph,
nice questions, unfortunately I can hardly answer any of them.
for the fillingscme so far:
single_3b_2_2_2_wp f.e. means:
| | | | | |
| | | | | --- I dont know
| | | | ------ 2 colliding bunchpairs in LHCb
| | | -------- 2 colliding bunchpairs in Alice
| | ---------- 2 colliding bunchpairs in Atlas & CMS (they are exactly oposite of eachotther)
| ------------ 3 bunches per beam
------------------ I dont know
nice questions, unfortunately I can hardly answer any of them.
for the fillingscme so far:
single_3b_2_2_2_wp f.e. means:
| | | | | |
| | | | | --- I dont know
| | | | ------ 2 colliding bunchpairs in LHCb
| | | -------- 2 colliding bunchpairs in Alice
| | ---------- 2 colliding bunchpairs in Atlas & CMS (they are exactly oposite of eachotther)
| ------------ 3 bunches per beam
------------------ I dont know
bye
chriwi
chriwi
- DCWhitworth
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Re: Why So QUIET ??? Machine Development !!!!!
I think the 'single' refers to the number of bunches per injection.chriwi wrote:Hi gilgamorph,
nice questions, unfortunately I can hardly answer any of them.
for the fillingscme so far:
single_3b_2_2_2_wp f.e. means:
| | | | | |
| | | | | --- I dont know
| | | | ------ 2 colliding bunchpairs in LHCb
| | | -------- 2 colliding bunchpairs in Alice
| | ---------- 2 colliding bunchpairs in Atlas & CMS (they are exactly oposite of eachotther)
| ------------ 3 bunches per beam
------------------ I dont know
DC
The LHC - One ring to rule them all !
The LHC - One ring to rule them all !
Re: Why So QUIET ??? Machine Development !!!!!
OK Lets give it a go ....
By the way, 25ns corresponds to a physical separation of 7.5m
The ATS scheme uses a "classical" Squeeze technique to reach ~40cm then a very special distortion of the optics of the adjacent octants to lower it further (this does not compute correctly on the configuration page). 20cm was reached for both beams. Unfortunately 1 beam was lost in going to 10cm due to a setting error.
...the filling scheme seems to have been explained elsewhere ...
25ns is the distance between 2 adjacent bunches which are delivered from the injectors. It only makes sense in multi-bunch injections. A maximum of 72 bunches can be created in the PS with a spacing of 25ns. 4 of these can be put together in the SPS to make 288 bunches in total. However between each batch of 72 bunches there is a slightly larger gap to allow clean transfer between the PS and SPS....25 ns. . . . . new settings !! . . . . . . .
(what does 25ns mean if you are injecting one bunch ? just a doubled RF ?)
By the way, 25ns corresponds to a physical separation of 7.5m
Chromaticity is the dependence of the focusing on momentum. In optical terms it is a little like chromatic aberration. There is always an energy spread in the bunch - therefore individual particles will see different focusing. In addition, due to synchrotron motion, the energy of each particle wil vary in time within the bunch..latest-news @ 12:04 - 288 b stable with high chromaticity
whew .... by chromaticity are they refering to spread in kinetic energy in the bunch?
ATS: Achromatic Telescopic Squeeze.2) ATS ! there must be dozens, if not hundreds of random physics anagrams that match.
I go on record with a random guess of Advanced Tracking System.
Jeez there is a lot here ...
3) I was unable to watch the entire ultralow beta* squeeze
I gather that the target was beta*=0.10m at IP1 and IP5 and the OP Vistars view at LHC configuration seemed to indicate that an eight hour squeeze was unsuccessful. Beta* minned out at 0.55m. Although increased squeeze occurred IP2 (5.33->4.92->4.16) and at IP8 (3.14->3.07->2.81) the configuration page showed no change at IP1 and IP5.
After they lost beam1 (@ ~2:50) the operator commented:
@ 2:59:42 beta* = 14 cm Only for beam2 . . .
@ 3:13:40 ATS MD 10 cm beta* optics measurement
Does anyone know how quickly they were able to achieve beta*=0.55m ?
Any comments on why LHC Configuration page never showed the beta* values that the operator quoted ?
The ATS scheme uses a "classical" Squeeze technique to reach ~40cm then a very special distortion of the optics of the adjacent octants to lower it further (this does not compute correctly on the configuration page). 20cm was reached for both beams. Unfortunately 1 beam was lost in going to 10cm due to a setting error.
...the filling scheme seems to have been explained elsewhere ...
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- Joined: Sat Apr 28, 2012 5:48 am
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Re: Why So QUIET ??? Machine Development !!!!!
Thanks Chriwi, DC.
I appreciate your insights pcatom, an excellent explanation.
Your comments on chromaticity and ATS were succinct and much appreciated.
re: filling scheme; Chriwi and DCWhitworth elucidated the parts I knew. I was looking for an explanation of the postfaces seen in recent weeks that I've no clue about. Current fills end in _wp and prior to TS2 there was a fill with _nLR at the end of the AFS.
Again, Thanks Greatly for your assistance.
I appreciate your insights pcatom, an excellent explanation.
Sorry, I was facetiously riffing on the single bunch pilot probe that they injected. I'm glad to learn about the PS/SPS limitations on bunch length. It explains their excitement at 288 bunch injections - that much closer to maximum possible luminosity!25ns is the distance between 2 adjacent bunches which are delivered from the injectors. It only makes sense in multi-bunch injections.
Your comments on chromaticity and ATS were succinct and much appreciated.
re: filling scheme; Chriwi and DCWhitworth elucidated the parts I knew. I was looking for an explanation of the postfaces seen in recent weeks that I've no clue about. Current fills end in _wp and prior to TS2 there was a fill with _nLR at the end of the AFS.
Again, Thanks Greatly for your assistance.