PERFORMANCE ANALYSIS OF MULTI-TURN EXTRACTION FROM THEPROTON SYNCHROTRON TO THE SUPER PROTON SYNCHROTRON

Sam Abernethy1

1Department of Physics, Engineering Physics and Astronomy,64 Bader Lane, Queen’s University, Kingston, Canada

Within CERN’s accelerator complex, the extraction from the Proton Synchrotron to the SuperProton Synchrotron has been done using the so-called “Continuous Transfer” (CT) method sincethe 1970’s. A new technique, known as Multi-Turn Extraction (MTE), has now been implementedand is in full operation. This report examines a holistic performance analysis of the novel techniquein multiple aspects of the accelerator complex, as well as a direct comparison with its predecessor,CT, from the implementation of MTE in 2010 until the end of 2015.

I. INTRODUCTION

The main purpose of this report, and my project overthe summer, was to construct a framework with which toconduct a performance analysis of Multi-Turn Extraction(MTE). In Section I A, I will lay out a very brief intro-duction to the extraction from the Proton Synchrotron(PS) to the Super Proton Synchrotron (SPS), as well asdiscuss the details of MTE. In Section I B, the figures ofmerit needed to conduct a performance analysis are de-fined and discussed. In Section II, the full performanceanalysis will be conducted, before drawing conclusionsand examining future investigations in Section III.

A. Extraction from PS to SPS

The method of beam extraction from the PS to theSPS that had been in use since the 1970’s, ContinuousTransfer (CT) was based on beam slicing in the horizon-tal plane with an electrostatic septum. By setting thetune to 6.25, the beam rotated by 90◦ in phase space af-ter each revolution in the PS. Using this technique, thebeam could be extracted over five turns, and sent to theSPS, via the Transfer Lines (TL). Since the SPS is 11times as long as the PS, this five turn extraction filled511 of the SPS, meaning that two full extractions wereneeded to “fill” the SPS, while leaving some space forlogistical reasons. This is shown visually in Fig. 1 [1].

FIG. 1: Basic model of CT extraction.

The main drawbacks of CT were that it caused highradiation levels in the PS, as well as an inconsistentphase shape in the extracted beam. As a result, a noveltechnique was proposed in 2002: Multi-Turn Extraction(MTE).

MTE is based on an adiabatic crossing of resonanceexcited by sextupoles and octupoles, in which particlesare trapped in stable islands of low-order 1D resonancesof horizontal phase space. In less technical terms, thebeam is split (via time-evolving magnetic fields) into a“core” and four outer islands. Fig. 2 offers a visualrepresentation of the trajectories of the islands [1].

FIG. 2: Evolution of the beam over time; each color rep-resents one of the four outer islands, while the core travelsalong the center, shown in black.

After being proposed in 2002, it wasn’t until 2010 thatthe first extraction was completed using MTE. At thattime, there were large fluctuations in the efficiency overtime. After a prolonged effort by many involved with theCERN Beams Department, this fluctuation was trackeddown to be caused by a 5 kHz modulation and was largelyreduced. As a result of this, MTE officially replaced CTin September 2015 and has been used to extract beamfrom the PS to the SPS since then.

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B. Figures of Merit

The natural figure of merit for MTE is “MTE effi-ciency,” or ηMTE. Based on the four outer islands and thecore having different intensities, it is a measure of whatfraction of the beam is trapped in the outer islands:

ηMTE =〈IIslands〉ITotal

(1)

In this equation, 〈IIslands〉 and ITotal stand for the aver-age intensity in the islands and the total beam intensity,respectively. The nominal MTE efficiency is 0.2, whichcorresponds to equal intensities in the islands and thecore.

Another figure of merit is ηDC, which can be inter-preted as a measure of variability between island inten-sities (assuming no underlying structural symmetry):

ηDC =1

T

[∫ T

0

I(t) dt

]2

∫ T

0

I2(t) dt

(2)

II. PERFORMANCE ANALYSIS

The quantitative analysis of the novel MTE techniqueis performed by considering the PS and SPS rings, first asseparate entities, and then by looking for correlations be-tween the two machines. This is imposed by the presentstate of MTE, in which fluctuations of the beam param-eters are still present, although at a reduced level withrespect to the initial beam commissioning. Then, a di-rect comparison between CT and MTE is carried out toassess the improvements already achieved and the areasstill requiring further attention.

For the performance analysis, certain time frames werechosen to analyze from 2010 (for initial MTE operationalimplementation) as well as 2015 [1] runs. For 2015, onetime frame was chosen as representative of the CT ex-traction technique on September 19th, which was nearthe end of CT usage. For the MTE data in 2015, theintensity Np was tested in three separate time frames toprobe the following values: 1500, 1800, and 2000, all in1010 ppp. Note that while the first value had been inoperation for few weeks, the intermediate one was usedfor SPS filling only for some hours, on the move towardsNp = 2000 × 1010 ppp, which was the interesting valuekept until the end of the 2015 run. The overall pictureis shown in Fig. 3, where the PS beam intensity and theextraction efficiency are plotted as a function of time.

To carry out the full performance analysis, certain cutshad to be made on the beam intensity entering the PSand SPS, so as to remove data that was anomalous andvaried too widely from the configuration to which the

Np = 15000

500

1000

1500

2000

Inte

nsity

 [10

10 p

pp]

IntensityCutoffsηMTE

Np = 1800 Np = 20000.16

0.18

0.20

0.22

0.24

0.26

0.28

0.30

η MT

E [­

]

FIG. 3: PS intensity over time, shown together with thecuts in intensity, and ηMTE.

machines were calibrated. In Fig. 3, the raw data forPS intensity is shown before any selection is made, alongwith the implemented cuts in intensity and correspondingηMTE over time. The cuts used for all time frames arealso summarized in Table I.

Nominal PS SPS RemovedIntensity Cutoff Cutoff data [%]

1500 < 1400 or > 1600 < 2600 11.1MTE 1800 < 1700 or > 1900 < 3050 30.2

2000 < 1850 or > 2050 < 3400 19.3CT 1600 < 1500 or > 1700 < 2850 10.4

TABLE I: Intensity selection ranges (all units, unlessotherwise specified, are 1010 ppp). The large percentage

of data removed from the sample corresponding toNp = 1800 is due to the period near the start in which

the intensity was too high.

A. Proton Synchrotron

The analysis of the PS performance is based on threemain figures of merit, namely ηMTE, ηDC and ηExt. Thefirst two have been already defined, while the last one isPS extraction efficiency. This is obtained by comparingthe intensity prior to extraction, as measured by a currenttransformer in the PS, to the measurement from a currenttransformer at the beginning of the transfer line.

To evaluate ηMTE and ηDC, the extracted beam in-tensity I(t) (also called spill in the following) must beexamined. The spill can be acquired by either a low- ora high-sampling rate device. Given the large amount ofdata generated by the latter, the data used for the anal-ysis reported in this paper is based on the low-samplingrate device. However, for a specific data sample a de-tailed comparison of ηMTE and ηDC provided by the twodevices has been carried out and a very good correlationwas found (featuring a correlation factor ρ around 0.99).

An example of a typical spill for both CT and MTE

3

can be seen overlaid on top of each other in Fig. 4. Thesespills have been calculated by restoring the baseline lin-earity, which is distorted by the electrical properties ofthe circuits, and by suppressing the resulting constantbaseline [2]. It is important to note that the main dif-ference between the two techniques is that the slope ofthe spill, both at the start and end of extraction, is muchsteeper for MTE, due to faster kicker rise time in com-parison with the CT fast dipoles.

2 4 6 8 10 12 14 16 18 20Time [µs]

0.0

0.2

0.4

0.6

0.8

1.0

Spi

ll [a

. u.]

CTMTE

FIG. 4: Example spill for both CT and MTE.

A histogram of ηMTE can be seen in Fig. 5. By com-paring the 2010 data to 2015, it is clear that there hasbeen a marked improvement in ηMTE, which indicatesthat the sharing between the beam trapped in the is-lands and that left in the core has been pushed towardsthe nominal value of ηMTE, i.e., ≈ 0.2. Similarly, ηDC

can be calculated for MTE and CT, and this is shownin Fig. 5. ηDC has also increased significantly from 2010with the MTE technique, at the same time reducing theoverall spread, which is a clear indication that the spillshape is flatter and closer to the ideal situation of a con-stant intensity during the five turns of the extraction.

In terms of PS extraction efficiency, it is worth men-tioning that this figure of merit depends on the calibra-tion used to standardize the two devices used to measurethe intensity in the PS and in the transfer line. The ap-proach used to determine the calibration of the beam cur-rent transformer in the transfer line has been much im-proved over the years [3], thus making it difficult to com-pare the results obtained in 2010 with those of the recent2015 run. An indication of the potential issues with thecross-calibration of the PS and transfer line transformersis given by the presence of values of ηExt ≥ 100 %, whichare clearly non-physical. This situation is not present inthe 2015 data, while for the 2010 sample ηExt goes upto 101.2%. As a result, the offset in the calibration pro-cedure was determined to be incorrect and it has beenshifted (by 2% in the calculated PS extraction efficiency)so as have the maximum PS extraction efficiency below100 %. A histogram of ηExt after this offset correctionwas performed, can be seen in Fig. 6 (upper part). Theimprovement in terms of extraction efficiency in 2015 over

0.15 0.16 0.17 0.18 0.19 0.20 0.21 0.22ηMTE [­]

0

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Dis

trib

utio

n [­

]

Np = 2000

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MTE (2010)

0.95 0.96 0.97 0.98 0.99 1.00ηDC [­]

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400

Dis

trib

utio

n [­

]

Np = 2000

Np = 1800

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CTMTE (2010)

FIG. 5: Upper: Histogram showing the distribution ofthe MTE efficiency. Lower: Histogram showing the

distribution of the DC efficiency from 2010 until 2015,including CT data.

2010 is clearly visible, not only in terms of a higher valueof the average ηExt, but also in terms of the shape andpopulation of the tail towards low values of the extrac-tion efficiency, which is much reduced for the 2015 datasample.

Similarly, an efficiency for the transfer line has beendefined using as boundaries the first current transformerout of the PS ring, i.e., the same device used for ηExt, andthe last device before the injection point into the SPS.The distribution of this figure of merit is also shown inFig. 6. Data for the 2010 run wasn’t taken, thus prevent-ing a direct comparison between the two runs. Nonethe-less, the distributions are nicely peaked, without tails,indicating that the fluctuations in ηMTE are not affectingthe performance of the beam transfer between the tworings (see later).

The last observation, already made in [1], is that onlya very mild dependence on the beam intensity is found inthe 2015 data, which is certainly an important point forfuture developments with higher intensity beams. Thepositive trend in the key figures of merit since the firstMTE implementation in 2010, can be seen in Fig. 7.

The key figures of merit ηMTE, ηDC, ηOverall (see nextsection for the definition of ηOverall) are shown for the2010 and 2015 MTE runs. For the 2015 case, the beam

4

90 92 94 96 98 100ηExt [%]

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4D

istr

ibut

ion 

[­]

Np = 2000

Np = 1800

Np = 1500

CTMTE (2010)

90 92 94 96 98 100ηTL [%]

0.0

0.5

1.0

1.5

2.0

2.5

Dis

trib

utio

n [­

]

Np = 2000

Np = 1800

Np = 1500

CT

FIG. 6: Upper: Histogram showing the distribution ofthe PS extraction efficiency. Lower: Histogram showing

the distribution of the transfer line transmissionefficiency.

performance at the beginning of the MTE run, whichstarted late in September, as well as during the threetime frames with increasing intensity are shown. Theimprovement of ηMTE with respect to 2010 and also in2015 with respect to the beginning of the run is clearlyvisible.

B. Super Proton Synchrotron

The standard approach used to qualify the SPS perfor-mance is based on the definition of key times along themagnetic cycle at which the transmission efficiencies areexamined. The names for these times (and their abbrevi-ations) are as follows: Injection (Inj), Flat Bottom (FB),Front Porch (FP), Transition (Tr), and Flat Top (FT).These times can be seen in Fig. 8 where the evolution ofthe beam intensity and momentum is shown as a functionof time. Note also that transmission efficiencies withinthe SPS are defined in terms of the transmission from theprevious stage to the stage named. As an example, ηTris defined as the percentage of intensity at FP that getstransmitted to Tr.

It is worth stressing that two extractions from the PS

20100.16

0.18

0.20

0.22

0.24

0.26

0.28

0.30

η MT

E [­

]

20150.75

0.80

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0.90

0.95

1.00

η DC

 [­]

65

70

75

80

85

90

95

100

η Over

all [

­]

FIG. 7: MTE figures of merit over time(ηMTE, ηDC, ηOverall, see next section for the definitionof ηOverall). For all three figures of merit shown herethere is an improvement from 2010 to 2015 in their

values as well as a reduction in the standard deviation(corresponding to the size of the error bars), indicating

an increased reproducibility.

1500 2000 2500 3000 3500 4000 4500Time [ms]

2600

2650

2700

2750

2800

Inte

nsity

 [10

10 p

pp]

InjFBFPTrFT

0

100

200

300

400

500

Mom

entu

m [G

eV/c

]

FIG. 8: Example of beam intensity in the SPS as afunction of time. Key times shown are Inj, FB, FP, Tr,

and FT.

are injected into the SPS, separated by 1.2 s (the PS cyclelength for accelerating protons to 14 GeV/c). The SPSInjection Efficiency is the sum of the injected intensitiesof the two beams from the transfer line, divided by thesum of the two beams’ intensities in the transfer line justupstream of the injection point in the SPS.

The distribution of the efficiencies at the various keytimes are reported in Fig. 9 for the three intensity valuesused in 2015, including also comparative data from theCT. Wherever possible, the data from the 2010 MTErun is included in the analysis. Similarly to what wasobserved in the PS, a sizeable improvement is visible bothin terms of mean and rms values of the distribution of theefficiency figures compared to 2010. The other importantaspect is that the SPS performance clearly depends onthe beam intensity, unlike in the PS in which no or onlymild dependence on beam intensity was observed.

A metric for the overall SPS performance is given by

5

90 92 94 96 98 100ηInj [%]

0.0

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2.0

Dis

trib

utio

n [­

]

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CT

90 92 94 96 98 100ηFB [%]

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]

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CTMTE (2010)

90 92 94 96 98 100ηFP [%]

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]

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CTMTE (2010)

90 92 94 96 98 100ηTr [%]

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90 92 94 96 98 100ηFT [%]

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]

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CTMTE (2010)

90 92 94 96 98 100ηSPS [%]

0.0

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1.5

2.0

2.5

3.0

Dis

trib

utio

n [­

]

Np = 2000

Np = 1800

Np = 1500

CTMTE (2010)

FIG. 9: Global picture of the distribution of the beam transmission through the SPS cycle at key times.

the SPS transmission efficiency, ηSPS, defined in terms ofthe intensity at the end of the SPS cycle (at FT) dividedby the sum of the two beams’ intensities before ejectionin the PS. The histogram is shown in Fig. 9 (lower rightplot), where the overall improvement of the transmissionefficiency over time is clearly visible and, as expected,features a dependence on beam intensity. ηSPS is notthe unique indicator of global performance for the MTEbeam as one can also include the PS, providing a figure ofmerit for the efficiency between PS injection and SPS atFT. This indicator is called ηOverall and its distribution isshown in Fig. 10. Once more, the MTE improvement overthe years is clearly seen as well as a certain dependenceon the beam intensity.

The last point to consider is that the previous efficiencyindicators, which reflect a time dependence of the losses,

can provide insight into the losses distribution as a func-tion of beam momentum. This aspect is essential whenevaluating the overall performance of MTE beams, i.e.,looking at both machines, PS and SPS, and not focusingon a single one. Indeed, higher-energy particles producedifferent effects in terms of irradiation and activation,which makes the momentum distribution of beam lossesan essential figure of merit. The situation is summarisedin Fig. 11. After a full analysis of the intensity lossesas a function of momentum, the most significant con-tribution to the lost intensity comes around 22 GeV/c,corresponding to transition crossing, and the second sig-nificant contribution occurs at injection energy. In theother parts of the SPS cycle the losses are negligible.

6

70 75 80 85 90 95 100ηOverall [%]

0.0

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1.0

1.2D

istr

ibut

ion 

[­]

Np = 2000

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Np = 1500

CTMTE (2010)

FIG. 10: Histogram showing the distribution of ηOverall.

14 16 18 20 22 24Momentum (GeV/c)

0.0

0.5

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2.0

2.5

3.0

Inte

nsity

 Los

ses 

(%)

Np = 1500

Np = 1800

Np = 2000

CT

FIG. 11: Intensity losses in % as a function ofmomentum for 2015 data, both CT and MTE. The

highest intensity losses (for all four time frames) comearound 22 GeV/c, corresponding to transition crossing,

reaching as high as 2.5%.

C. Correlations between PS and SPS

The presence of time variations in the main PS beamparameters like ηMTE induces variations in SPS perfor-mance. Therefore, a statistical analysis of the correlationbetween the key efficiencies of the two machines is neededto assess which parameter has the greatest effect on theoverall performance.

It is worth noting that whenever the PS and SPS dataare to be considered globally, the two PS cycles, whichare injected in the same SPS cycle, should in some sensebe combined together. For example, the analysis of thecorrelation of ηMTE for two PS consecutive cycles shows avery strong correlation (higher than 0.80) for all data setsexamined. This means that the time variations are on alonger time scale than that of the duration of the pairsof 14 GeV/c PS cycles. For this reason, the efficiencyindicators of PS cycles injected into the same SPS cy-cle have been averaged for use in the analysis presented.Furthermore, all SPS cycles in which a single injection

from the PS was performed have been rejected and arenot part of the data sample discussed.

The correlation analysis outcome is summarised inFig. 12, where the elements of the correlation matrix areshown as heatmaps. Given the intrinsic symmetries, onlythe lower-diagonal part of the matrix is shown.

The first conclusion one can draw from the plots is thatthe overall pattern does not depend strongly on beamintensity. The second immediate conclusion from theseheat maps is that there is a rather strong correlation be-tween ηMTE and ηExt for all three MTE time frames,which represents a correlation between figure of meritsin the same ring. The third conclusion is that the corre-lations between ηMTE and SPS efficiency figures are notvery strong. This is an important outcome of the anal-ysis, i.e., that the shape of the spill does not seem to bethe main culprit for the SPS performance. In fact, ηMTE

is positively correlated with losses earlier in the transmis-sion through the SPS cycle (such as ηTL, ηInj), but lesscorrelated with later transmission efficiencies. Further-more, the stronger correlation is only between ηExt andηInj, suggesting that improving the PS extraction willlead to more effective injection into the SPS. Note thatηInj is less strongly correlated with ηMTE thus indicatingthat a flat spill is less important, as far as SPS injectionlosses are concerned, than a clean PS extraction. It isalso worth mentioning that most of the correlations arepositive, indicating that an improvement in the PS wouldalso be beneficial for the SPS.

To examine this further, the correlation plots for someof the SPS efficiencies against ηMTE are shown in Fig. 13.The progressive reduction of the correlation of SPS fig-ures of merit and ηMTE is clearly visible as well as a non-negligible number of outliers: in spite of their impact onthe numerical value of the correlation, which could behigher if we rejected outliers, the plots clearly indicatethat the reduction of correlation is real.

7

ηMTE ηExt ηTL ηInj ηFB ηFP ηTr

η FT

η Tr

η FP

η FB

η Inj

η TL

η Ext

0.20 ­0.01 0.05 ­0.08­0.06­0.09 0.30

0.11 ­0.08­0.05­0.03­0.05­0.14

0.38 0.57 0.15 0.69 0.61

0.13 0.19 0.03 0.75

0.42 0.47 0.10

0.38 0.26

0.75

ηMTE ηExt ηTL ηInj ηFB ηFP ηTr

η FT

η Tr

η FP

η FB

η Inj

η TL

η Ext

0.33 0.01 0.07 ­0.08­0.04­0.02 0.48

0.39 0.15 0.03 ­0.24­0.08 0.15

0.45 0.50 0.20 0.36 0.58

0.31 0.41 0.21 0.73

0.26 0.48 0.28

0.34 0.32

0.72

ηMTE ηExt ηTL ηInj ηFB ηFP ηTr

η FT

η Trη F

Pη F

Bη I

njη T

Lη E

xt

­0.16­0.00 0.10 0.10 ­0.02­0.05 0.27

­0.06 0.26 0.05 0.32 ­0.08 0.00

0.10 0.24 ­0.05 0.44 0.81

0.05 0.17 ­0.01 0.48

0.23 0.57 ­0.27

0.22 0.16

0.71

0.8

0.4

0.0

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0.8

Cor

rela

tion

FIG. 12: Correlation heat maps for the figures of merit used in the analysis. The three plots refer to the differentMTE beam intensities, namely Np = 1500, 1800, 2000 ppp for the left, centre, and right panel, respectively. It is

worth noting the general tendency of correlations to be positive.

0.16 0.17 0.18 0.19 0.20 0.21 0.22ηMTE [­]

90

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[%]

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 [%]

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[%]

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Np = 2000

FIG. 13: Example of correlation plots between PS andSPS efficiency figures of merit. The progressively lowercorrelation between ηMTE and transmission efficienciesfor later stages in the SPS cycle is clearly visible.

D. Comparison between CT and MTE beams

The last point that will be addressed is the direct com-parison between CT and MTE. The key quantities havebeen already shown in previous plots and in this sectionthe main points will be presented. At the level of the PSring, the MTE features a flatter spill than CT as can beseen in Fig. 5, where the distribution of ηDC is shown. Infact, even though MTE features longer tails in the dis-tribution of ηDC, the minimum value is still comparablewith that of CT and the peak is much closer to 1. More-over, MTE is also superior in terms of ηExt (see Fig. 6).The transfer line efficiency ηTL features very similar dis-tributions for CT and MTE.

As far as the SPS ring is concerned, the situation issomewhat different. The overview of the figures of meritreported in Fig. 9 is rather clear: in general, CT performsbetter than MTE, with narrower distributions, shiftedtowards higher values of efficiencies. The differences areparticularly striking in the low-energy part of the SPSmagnetic cycle, while they are reduced at higher energiesand after transition no notable differences are found. Asa result, ηSPS is rather different (see Fig. 9, lower right)for CT and MTE, mainly due to the differences in thelow-energy regime of the SPS cycle. A somewhat dif-ferent situation is found considering ηOverall, where themain difference between CT and MTE is the spread ofthe distributions, while the mean values are comparable.The losses vs. beam momentum shown in Fig. 11 con-firms what was already mentioned, i.e., that in the SPSthe losses for MTE are larger than for CT up to aroundtransition and then the differences are no longer relevant.

In terms of correlation between PS and SPS perfor-mance, it is interesting to compare the heat maps forMTE, as seen in Fig. 12, and the corresponding situationfor CT, as seen in Fig. 14.

8

ηMTE ηExt ηTL ηInj ηFB ηFP ηTr

η FT

η Tr

η FP

η FB

η Inj

η TL

η Ext

­0.06­0.03­0.06 0.08 ­0.02 0.09 ­0.05

­0.24­0.03­0.15 0.07 ­0.02 0.18

0.02 ­0.02 0.00 0.19 0.50

­0.06­0.15­0.02 0.35

­0.18­0.02­0.58

0.33 0.18

0.34

0.8

0.4

0.0

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0.8

Cor

rela

tion

FIG. 14: Correlation heatmap for the figures of meritused in the analysis of CT performance.

The difference between MTE and CT is remarkable:while some correlation can be found for MTE, with CTall correlations are rather weak, as the largest ones are ofthe order of 0.5 in absolute value. This could be partlydue to the smaller fluctuations in the efficiency figures ofmerit for CT than for MTE (see, e.g., Fig. 9).

As a last point, another way of directly comparing CTand MTE consists of examining the information from theindividual beam loss monitors (BLMs) that are installedalong both the PS and SPS circumference. For the PSBLMs, Fig. 15 shows the striking improvement of MTEwith respect to CT. This is the consequence of the MTEprinciple, which avoids the beam slicing with an electro-static septum, leading to a dramatic reduction of beamlosses around the PS ring. Note that the plot has beengenerated using data with Np = 1500 (the closest inten-sity to that of the CT time frame) and the overall patternof losses does not differ when other intensities are used.The SPS situation is also visible in Fig. 15. These lossesare scaled by the intensity of the beam, so as to give a di-rect comparison. In most of the BLMs, there are similarlevels of losses, but in BLM 121 there is a clear intensitydependence, with an increase of a factor of 2 or morewhen the highest intensity (Np = 2000) is used.

To summarize the current breakdown of where thelosses come from in the PS to SPS extraction mecha-nism, Fig. 16 shows the losses in each of the four majorsections (PS Extraction, Transfer Lines, SPS Injection,and SPS Overall transmission). For the 2010 run, nodata is available to evaluate the losses in the transfer lineand at SPS injection, so they have been left as 0.0% (toonly compare like to like), but the dashed line at the topof the figure shows the overall losses in 2010.

00 05 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95

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]

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FIG. 15: BLM readings for MTE and CT in the PS (up-per) and SPS (lower) rings. For the PS case the readingsare given in ADC counts, while for the SPS, the readingshave been normalised to the beam intensity.

MTE (2010) CT Np = 1500 Np = 1800 Np = 20000

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nsity

 Los

ses 

(%)

3.90.00.0

10.5

5.7

3.71.11.6

2.43.51.7

6.1

2.33.5

5.0

4.8

2.53.7

3.0

6.2

Total Losses for MTE (2010)PS Extraction LossesTransfer Line LossesSPS Injection LossesSPS Transmission Losses

FIG. 16: Bar Plot of Losses for MTE and CT beams.The height of each bar represents the total losses, frombefore ejection in the PS, to FT in the SPS.

9

III. CONCLUSIONS AND FUTURE WORK

The first point to note is the huge improvement inMTE global performance since 2010, in all aspects ofthe accelerator complex. The primary improvement ofMTE over CT is found in the PS, where losses have beenreduced from 5.7% to roughly 2.4%. The situation inthe SPS still favours CT, as far as beam losses are con-cerned, even while the combined losses in the PS andSPS are almost the same for MTE and CT. It shouldnot be forgotten that CT was implemented in the 1970’s,fully optimized over the course of decades, and the levelof losses shown in Fig. 16 are the results of long andmeticulous work. Clearly, MTE is comparatively verynew and still has room for major improvements, but israpidly increasing efficiency over the years.

Efforts are ongoing in the CERN Beams Departmentto further improve efficiency, determine correlations be-tween figures of merit, and investigate sources of lossesthroughout the accelerator complex. This performanceanalysis framework, constructed to analyze the 2015data, will continue to be used to examine the 2016 datalater this year.

IV. ACKNOWLEDGEMENTS

It is with sincere appreciation that I thank Dr. Mas-simo Giovannozzi and Dr. Guido Sterbini for their super-vision and guidance throughout my summer at CERN. Iwould also like to thank Dr. Adam Sarty and the Insti-tute of Particle Physics, as well as the CERN SummerStudent Programme, for making this fantastic experiencepossible.

[1] J. Borburgh, S. Damjanovic, S. Gilardoni, M. Giovan-nozzi, C. Hernalsteens, M. Hourican, A. Huschauer,K. Kahle, G. Le Godec, O. Michels, G. Sterbini, EPL 11334001 (2016).

[2] J. Bellemann, private communication (2016).[3] L. Soby, private communication (2016).