Tine and Losses Panel in vistars

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ferar
Posts: 14
Joined: Mon May 10, 2010 2:44 am

Tine and Losses Panel in vistars

Post by ferar » Mon Sep 12, 2011 5:36 pm

Hello, looking at the vistars (meltronx.com) in one of the LHC dashboard panels you can see Tune and Losses. I tried but could not understood some of the panels, if someone is so kind to explain It will be very welcomed. http://lhclite.meltronx.com/dash.html

How Tune is read? Why are there multiple spots from time to time?

Same thing for Losses, I someone can explain how is it read it will be great.

Thanks very much.
Regards;
fernando

jahonen
Posts: 7
Joined: Wed Sep 07, 2011 6:03 pm

Re: Tine and Losses Panel in vistars

Post by jahonen » Mon Sep 12, 2011 7:39 pm

The following is just my understanding of what you ask, someone please correct me if I am totally off-track.

You can find excellent description of the tune here among other beam parameters. Vertical position of the tune dot represents measured vertical tune and horizontal position of the dot the horizontal tune :) Lines crossing the graph represent resonance lines, so you don't want your dot to be at one. Resonance-free region (the box shown) is fairly small so good control of the tune is obviously required.

I think that multiple dots are due to that tune amplitude becomes low when transverse damper gain is turned up to stabilize the beam, so tune measurement becomes inaccurate.

Loss plot shows how much energy is lost from the beam to collimators and magnets etc. Unit is Gray = 1 Gy which means 1 J/(kg*s) = 1 W*s/kg. Less losses one sees, better the situation. The most losses are concentrated around points 3 (off-momentum collimators to clean out particles with wrong momentum) and 7 (transverse (betatron) collimators to clean out transversely off particles). There are also luminosity induced losses around experiments, which you can see around points 1, 2, 5 and 8.

Regards,
Janne

adam_jeff
Posts: 49
Joined: Thu Nov 18, 2010 3:07 pm

Re: Tine and Losses Panel in vistars

Post by adam_jeff » Tue Sep 13, 2011 12:31 pm

I could just add that in the loss map, the red marks represent the dump threshold or maximum allowed losses for each of the monitors. If the losses (green bars) reach the red mark at any point, the beam will be dumped.

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LarryS
Posts: 100
Joined: Fri Dec 04, 2009 3:46 pm
Location: Seymour, CT, USA

Re: Tine and Losses Panel in vistars

Post by LarryS » Tue Sep 13, 2011 1:43 pm

Thank you both for this information; the red marks had confused me for quite awhile.

jmc2000
Posts: 153
Joined: Sun May 08, 2011 2:51 pm

Re: Tine and Losses Panel in vistars

Post by jmc2000 » Fri Sep 16, 2011 8:31 pm

adam_jeff wrote:I could just add that in the loss map, the red marks represent the dump threshold or maximum allowed losses for each of the monitors. If the losses (green bars) reach the red mark at any point, the beam will be dumped.
So what are the blue bars?

ferar
Posts: 14
Joined: Mon May 10, 2010 2:44 am

Re: Tine and Losses Panel in vistars

Post by ferar » Sat Sep 17, 2011 5:40 pm

jahonen wrote:The following is just my understanding of what you ask, someone please correct me if I am totally off-track.

You can find excellent description of the tune here among other beam parameters. Vertical position of the tune dot represents measured vertical tune and horizontal position of the dot the horizontal tune :) Lines crossing the graph represent resonance lines, so you don't want your dot to be at one. Resonance-free region (the box shown) is fairly small so good control of the tune is obviously required.

I think that multiple dots are due to that tune amplitude becomes low when transverse damper gain is turned up to stabilize the beam, so tune measurement becomes inaccurate.

Loss plot shows how much energy is lost from the beam to collimators and magnets etc. Unit is Gray = 1 Gy which means 1 J/(kg*s) = 1 W*s/kg. Less losses one sees, better the situation. The most losses are concentrated around points 3 (off-momentum collimators to clean out particles with wrong momentum) and 7 (transverse (betatron) collimators to clean out transversely off particles). There are also luminosity induced losses around experiments, which you can see around points 1, 2, 5 and 8.

Regards,
Janne
Thanks very much Janne & Adam.
Really appreciate.
Cheers.
fernando

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