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1

ANALYSIS OF SOME LHC FILLS WITH AND WITHOUT TRANSV. EMIT. BLOW-UP

Elias Métral Info from Gianluigi: Fills with blow-up

• 1731 (36 bunches/train) – 480 bunches

• 1736 (72 bunches/train) – 480 bunches => BU or not? => No data

• 1744 (72 bunches/train) – 624 bunches

• 1756 (72 bunches/train) – 768 bunches => No data

Fills with no-blow-up

• 1732 (36 bunches/train) – 480 bunches

• 1736 (72 bunches/train) – 480 bunches => BU or not? => No data

• 1745 (72 bunches/train) – 624 bunches => Fill not found

• 1755 (72 bunches/train) – 768 bunches

Some other fills with in particular the fill 1802 (rec. lumi of ~ 1.1E33,

i.e. good) and the fill 1803 where BU has been observed

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2

480 bunches with 36 / train

(13 × 36 + 12)

Fill # 1731 => BU

Fill # 1732 => No BU

480 bunches with 36 / train

(13 × 36 + 12)

B1H mainly

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3

768 bunches with 72 / train

(10 × 72 + 1 × 36 + 12)

624 bunches with 72 / train

(8 × 72 + 1 × 36 + 12)

Fill # 1744 => BU

Fill # 1755 => No BU

B1H mainly

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CONCLUSIONS

It seems that for the cases where transverse emittance blow-up was observed,

some coherent motions were also observed from the BBQ:

With trains of 36 bunches => After ~ 9 trains, i.e. ~ 4E13 p total intensity

With trains of 72bunches => After ~ 6 trains, i.e. ~ 5.5E13 p total intensity

We will see later that with trains of 108 bunches => After ~ 2-3 trains, i.e. ~

3-4E13 p total intensity

We will also see that it usually starts in the H plane of either B1 or B2

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Meas. on 19/05/2011 (1/9)

LHC injections with batches of 108 bunches => Started at ~ 17:20

Chroma ~ 2 in both planes and beams and TD gain ~ 0.25 in both planes and

both beams.

1092 on B1 at 17:55

1092 on B2 at 17:56 => New record (it was 1020 for the scrubbing run)

Transverse emittances meas. by Kevin => Seems to reveal ~ 2.5 microm on B1

and ~ 3.5-4 on B2 with ~ constant values along the batch => No instability!

Finished with ~ 1300 bunches in both beams without strange signals on the

BSRT

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Meas. on 19/05/2011 (2/9)

1092 bunches with 108 / train

(10 × 108 + 12)

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Meas. on 19/05/2011 (3/9)

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Meas. on 19/05/2011 (4/9)

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Meas. on 19/05/2011 (5/9)

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Meas. on 19/05/2011 (6/9)

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Meas. on 19/05/2011 (7/9)

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Meas. on 19/05/2011 (8/9)

We had to kick (without beam) as we were close to a time-out for the injection

kicker => After this we saw some losses increasing on the TCTV.4R8 and we

lose on B2, which is the bigger beam

We got the OK to inject more bunches and we will try and do this soon (19:24)

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Meas. on 19/05/2011 (9/9)

1200 bunches with 108 / train

(11 × 108 + 12)

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2nd meas. on 19/05/2011 (1/3)

768 bunches, with batches of 72 bunches, in stable beams => ~

7.5E32 peak luminosity

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2nd meas. on 19/05/2011 (2/3)

768 bunches, with batches of 72 bunches, in stable beams => ~

7.5E32 peak luminosity

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2nd meas. on 19/05/2011 (3/3)

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Fill # 1802 on 23/05/11 with peak lumi ~ 1.1E33 (1/2)

912 bunches, with batches of 108 bunches (874 colliding pairs), in

stable beams => ~ 1.1E33 peak luminosity, which would mean ~ 2.5

microm transverse emittances => 1st time we went above 1E33!

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18

Fill # 1802 on 23/05/11 with peak lumi ~ 1.1E33 (2/2)

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Fill # 1803 with BU (1/6)

912 bunches, with batches of 108 bunches (874 colliding pairs), in

stable beams => ~ 0.85E33 peak luminosity, which would mean larger

transverse emittances as before (~ 3.2 microm) and therefore BU!

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Fill # 1803 with BU (2/6)

Activity in B2H just after 2nd batch

injected for B2

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Fill # 1803 with BU (3/6)

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Inj. of 2nd batch at ~ 08:19:53

08:19:56 => Black

08:19:58 => Blue

08:19:56 => Black

08:20:07 => Green

08:19:56 => Black

08:20:19 => Red

Appearance of some lines here (-1,

0, 1) Mode 0 growing faster

Fill # 1803 with BU (4/6)

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08:20:01 => Purple

08:20:13 => Light blue

Fill # 1803 with BU (5/6)

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=> Some lines (-1, 0, 1) seem to appear but there is no beam loss

during this process, only some transverse emittance blow-up

Mode 0 seems to grow faster than the others

I would expect some beam losses from the TCBI… Furthermore, the

instability rise-times predicted are smaller than 1 s, whereas here it

seems to be several s

Could this be due to some ecloud activity?

Could this be due to some residuals from the injection (from the

longitudinal plane as observed during the scrubbing run, or due to

the undamped oscillations, or from the injection or abort gap

cleaning)???

=> To be followed up

Fill # 1803 with BU (6/6)

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Comparison between fill 1802 good and 1803 bad, both with 920 bunches (1/14)

Fill # 1802 NicolasM

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Comparison between fill 1802 good and 1803 bad, both with 920 bunches (2/14)

Fill # 1803 NicolasM

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Comparison between fill 1802 good and 1803 bad, both with 920 bunches (3/14)

Fill # 1802 NicolasM

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Comparison between fill 1802 good and 1803 bad, both with 920 bunches (4/14)

Fill # 1803 NicolasM

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Comparison between fill 1802 good and 1803 bad, both with 920 bunches (5/14)

Fill # 1803 NicolasM

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Comparison between fill 1802 good and 1803 bad, both with 920 bunches (6/14)

Fill # 1802 NicolasM

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31

Comparison between fill 1802 good and 1803 bad, both with 920 bunches (7/14)

Fill # 1803 NicolasM

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Comparison between fill 1802 good and 1803 bad, both with 920 bunches (8/14)

Fill # 1803 NicolasM

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Comparison between fill 1802 good and 1803 bad, both with 920 bunches (9/14)

Fill # 1802 NicolasM

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Comparison between fill 1802 good and 1803 bad, both with 920 bunches (10/14)

Fill # 1803 NicolasM

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Comparison between fill 1802 good and 1803 bad, both with 920 bunches (11/14)

Fill # 1803 NicolasM

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36

Comparison between fill 1802 good and 1803 bad, both with 920 bunches (12/14)

Fill # 1803 NicolasM

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Comparison between fill 1802 good and 1803 bad, both with 920 bunches (13/14)

Fill # 1802 NicolasM

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Comparison between fill 1802 good and 1803 bad, both with 920 bunches (14/14)

Fill # 1803 NicolasM

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24/05/11: 1st bad fill and then refill and good fill (1/4)

UTC time here, i.e. – 2 h!!!

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24/05/11: 1st bad fill and then refill and good fill (2/4)

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24/05/11: 1st bad fill and then refill and good fill (3/4)

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24/05/11: 1st bad fill and then refill and good fill (4/4)

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29/05/11: 1st a bad fill and then a good one (1/?)

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29/05/11: 1st a bad fill and then a good one (2/?)

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29/05/11: 1st a bad fill and then a good one (3/?)

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29/05/11: 1st a bad fill and then a good one (4/?)

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29/05/11: 1st a bad fill and then a good one (5/?)

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31/05/11: Good and bad fills again BUT at different positions (1/?)

This beam was not accelerated due to BU. Note that usually the activity was after ~ 2 batches whereas it

is the 4th in this case (and it is B2V 1st here)

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31/05/11: Good and bad fills again BUT at different positions (2/?)

Excellent fill

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31/05/11: Good and bad fills again BUT at different positions (3/?)

The activity is now observed after the 8th batch!

(B1H)

Some pbs seen on this fill but it nevertheless gave an initial peak lumi of ~ 1.2E33! (only a bit less compared to the previous one)

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51

31/05/11: Good and bad fills again BUT at different positions (4/?)

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52

01/06/11: Today’s 3 fills would have been excellent with respect to intensity (~ 1.3E11 p/b => ~ 1.4E14 p) and

transverse emittances => No BU on 3 consecutive fills! (1/4)

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01/06/11: Today’s 3 fills would have been excellent with respect to intensity (~ 1.3E11 p/b => ~ 1.4E14 p) and

transverse emittances => No BU on 3 consecutive fills! (2/4)

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54

01/06/11: Today’s 3 fills would have been excellent with respect to intensity (~ 1.3E11 p/b => ~ 1.4E14 p) and

transverse emittances => No BU on 3 consecutive fills! (3/4)

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01/06/11: Today’s 3 fills would have been excellent with respect to intensity (~ 1.3E11 p/b => ~ 1.4E14 p) and

transverse emittances => No BU on 3 consecutive fills! (4/4)

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01/06/11: More analysis of these good fills! Why??? (1/?)

In fact the 4 consecutiverevealed no BU!!! (i.e. the one before

also)

Note also that contrary to what I thought we pulsed!

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57

01/06/11: More analysis of these good fills! Why??? (2/?)

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58

01/06/11: More analysis of these good fills! Why??? (3/?)

=> BU

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59

01/06/11: More analysis of these good fills! Why??? (4/?)

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60

01/06/11: More analysis of these good fills! Why??? (5/?)

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61

01/06/11: More analysis of these good fills! Why??? (6/?)

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62

01/06/11: More analysis of these good fills! Why??? (7/?)

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63

01/06/11: More analysis of these good fills! Why??? (8/?)

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01/06/11: More analysis of these good fills! Why??? (9/?)

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65

01/06/11: More analysis of these good fills! Why??? (10/?)

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01/06/11: More analysis of these good fills! Why??? (11/?)

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01/06/11: More analysis of these good fills! Why??? (12/?)

=> BU

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68

01/06/11: More analysis of these good fills! Why??? (13/?)

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69

01/06/11: More analysis of these good fills! Why??? (14/?)

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70

07/06/11: Bad fill again! (1/?)

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71

07/06/11: Bad fill again! (2/?)

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72

07/06/11: Bad fill again! (3/?)

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07/06/11: Bad fill again! (4/?)

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07/06/11: Bad fill again! (5/?)

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07/06/11: Bad fill again! (6/?)