Newsletter - Cern

Beams Department 

Issue 6 NEWSLETTER December 2012 

Inside This Issue 

p. 1 � Editorial – Ronny Billen 

p. 2 � HL-LHC Crab Cavities 

– Rama Calaga, BE-RF-BR 

p. 4 � LHC beam production in the PS 

– Christoph Kittel, BE-OP-PS 

p. 6 � Beta Beams for neutrino physics at CERN 

–Elena Wildner, BE-ABP-ICE 

p. 7 � CLIC through the eyes of art students 

– Mick Draper, BE-CO 

p. 9 � ACAS from the land Down Under 

– Ralph J. Steinhagen, BE-BI-QP 

p. 11 � Safety Column – BE Safety Unit 

Next issue 

The next issue will be published middle 

of April 2013. Contributions for that 

issue should be received by end of 

March at the latest. 

Suggestions for contributions are 

always most welcome: simply contact 

your Correspondent (see last page). 

Editorial 

Dear Readers, 

The end of the year is approaching fast and 

invitations for Christmas lunches, parties and 

drinks are starting to flow in. In order to relax 

the frequency of these exhausting events, our 

Department Head has shifted the annual 

Departmental meeting (followed by the 

traditional drink) to Thursday 17 January 2013. 

If this is not already highlighted in your agenda, 

mark it right now! 

In the meantime, most of you have been 

thoroughly preparing the (very) long shutdown 

LS1, not forgetting the (very) short technical 

stop around the Christmas break. Many of the 

installations – and the responsible personnel – 

will stay alert during this holiday period to 

anticipate a rapid and smooth restart for the 

proton-ion physics run. 

This 6 th BE newsletter has again a variety of 

interesting contributions from your colleagues 

of the respective groups. Learn all about the 

other BB (not the French actress Brigitte 

Bardot), eating habits in Australia, gymnastics 

in the PS, crustaceans in the LHC and fine arts 

in CLIC! I take the occasion to thank the 

authors very warmly and incite future 

contributors to contact their correspondent. 

Slightly ahead of time, I wish you all a welldeserved 

Christmas break. 

The Newsletter does not necessarily reflect the views of the Beams Department 

The contributions solely reflect the views of their author(s) 

Ronny Billen 

Editor, BE Newsletter

HL-LHC Crab Cavities 

The HL-LHC upgrade aims at reducing the beam 

sizes at the interaction points of ATLAS and CMS 

by approximately a factor of 2 to enhance the 

luminosity reach beyond the nominal LHC. Due to 

the common focusing channel in the interaction 

regions and small bunch spacing (25 ns), the two 

beams have to be separated transversely, 

horizontally or vertically to avoid parasitic collisions 

in the neighboring bunches. This separation leads to 

a non-zero crossing angle at the interaction point 

which is inversely proportional to the transverse 

beam size at the interaction point. As a consequence, 

the overlap of the colliding bunches for smaller 

beam sizes, with larger crossing angle, is less 

effective as depicted in Fig. 1 below. 

The incomplete overlap due to the crossing angle 

results in a luminosity reduction when compared to 

the case where bunches collide head-on. For 

bunches with a Gaussian distribution, this is 

conveniently expressed by the well-known Piwinski 

reduction factor 

1

esult of this R&D during the past 5 years, three 

compact designs at 400 MHz have emerged as 

potential candidates. They are not only smaller in 

transverse size by approximately 4 times than their 

conventional counterpart, but also exhibit superior 

RF properties. As a first step of RF design 

validation, all three cavities are being prototyped to 

undergo comprehensive tests to determine the best 

candidate for the LHC upgrade. These new 

topologies make it possible to integrate the 

cryomodules in the present LHC interaction region 

and also allow for the alternating crossing scheme 

(horizontal and vertical at IR1 and IR5 respectively) 

which is a prerequisite. 

Two of the cavity designs (see below: the 4-rod and 

the double ridge) have been prototyped using bulk 

Niobium metal in industry. They are pending surface 

and heat treatment before cryogenic and gradient 

testing this fall in the SM18 test facility and in the 

U.S. respectively. The fabrication of the third 

quarter wave design also using bulk Niobium is 

underway and expected to undergo tests early 2013. 

The timeline for R&D is synchronized with the 

present LHC running schedule and the HL-LHC 

project. Three clear milestones are set to determine 

the final construction of the hardware to become 

available for the final installation in the LHC circa 

2022-23. 

1. A validation of the three different cavity designs 

up to the nominal field in a vertical test setup is 

to take place by the end of 2012 with further tests 

continuing into 2013 and possibly beyond. 

2. At the same time, infrastructure preparation is 

foreseen during the upcoming long shutdown 

LS1 and subsequent technical stops in order to be 

able to carry out important beam tests in the SPS. 

This is essential; KEKB successfully 

demonstrated crabbing with electrons – no such 

tests have ever been done in a proton accelerator 

and, additionally, we must be sure there are no 

potential risks for LHC beam operation. A Crab 

Cavity Technical Coordination working group at 

CERN (CCTC) will identify and resolve all 

aspects related to such a test in the SPS. It is also 

foreseen that the test setup from the SPS can be 

transported to IR4 of the LHC for specific beam 

tests deemed necessary before installation of the 

complete systems in the LHC. 

3. Beam tests in the SPS with a prototype 

cryomodule and followed by tests in the LHC 

IR4 are therefore pre-requisites for a final 

installation in points 1 and 5. These tests have to 

take place well before the LS2 shutdown. 

3 Beams Department Newsletter Issue 6

Upon successful beam tests in the SPS and 

potentially in the LHC, construction of the final 8 

cryomodules to be installed at IP1 and IP5 will be 

launched. This final crab system will be realized as a 

joint effort with CERN, EuCARD, USLARP and 

other worldwide partners involved. An LHC HiLumi 

Design Study proposal to the European Union within 

the FP7 framework Protocol concerning the initial 

phase of the HL-LHC project, including a work 

package in Crab Cavities, was well received and 

given approval in 2010. 

Cavity design and test is of course only part of the 

crab cavity project. Many other systems are needed 

both in the tests and in the final system. For 

example a high performance low noise RF power 

system and associated controls are needed to 

precisely regulate the cavity fields at timescales of 

100µs. 

There will be challenges in the domains of controls 

and instrumentation demanding expertise from the 

CO and BI groups of BE. The cryogenic system to 

operate the cavities at 2K will be primarily 

developed at CERN. Considerable support will be 

needed from Engineering and Technology teams in 

the Accelerator sector. In parallel to the technology 

development, a significant effort to understand the 

beam dynamics aspects, cavity failure scenarios and 

the long term stability of the LHC beams in the 

presence of crab crossing, involving BE teams from 

ABP and OP, has started and will continue 

throughout the project. 

Rama Calaga, BE-RF-BR 

LHC beam production in the PS 

The integrated luminosity with proton-proton 

collisions in LHC just exceeded 20 inverse 

femtobarns with, in turn, lots of interesting physics 

results. However, in order to be able to achieve 

record luminosities and record fills, the injectors 

must perform as well at peak efficiency, producing 

the correct beam properties with the best possible 

beam quality. Prior to injection into the LHC, the 

beam has to undergo extensive manipulations in the 

injector chain to meet the high expectations. 

After leaving the source the beam passes through 

four accelerators before finally entering into the 

LHC at energy of 450 GeV. Each proton has then 

travelled already several million kilometers, many 

times the distance between earth and moon. 

The Proton Synchrotron (PS), third stage in the 

cascade of the four injectors, accelerates the proton 

beam from 1.4 to 26 GeV. The LHC multi-bunch 

beam is one of the most evolved ones, produced in 

the PS. This can be seen already from its cycle 

length of three basic periods, corresponding to 3.6 

seconds, the longest in PS. The demands on key 

parameters such as transverse beam size and equality 

of bunch intensities are constantly pushing the limits 

of PS. This explains why already the injection from 

the PS Booster (PSB) is special, done in two steps in 

order to keep a smaller transversal beam size. 

With the first PSB cycle one bunch from each ring is 

injected into four out of seven radiofrequency (RF)buckets. 

After staying 1.2 seconds at injection 

energy, a second PSB cycle injects two more 

bunches into the subsequent two RF-buckets. One 

RF-bucket remains empty, leaving a gap of at least 

300 ns, sufficient time to allow later the ejection 

kicker rising to full strength before kicking the beam 

in one turn into the transfer line towards SPS. 

The main task for the PS, next to the acceleration of 

course, is to generate the final longitudinal bunch 

spacing for the LHC (see Fig. 1). This involves 

different RF-manipulations. In all of them the 

number of RF-buckets per turn, expressed by the 

harmonic number of the RF, is changed. The 

harmonic number is the ratio between the frequency 

in the RF-cavity and the revolution frequency of the 

particles around the accelerator. 

Fig. 1 Splitting scheme of LHC beam in PS 

To split bunches in two parts the harmonic is 

doubled. The redistribution of the particles from one 


into two RF-buckets is done by reducing the voltage 

of the cavity with the lower harmonic, while 

increasing at the same time the voltage of the 

cavities with the higher harmonic and a phase shift 

of 180 degrees (see Fig. 2a). Without the phase shift 

however it is merely a harmonic number change, a 

so-called rebucketing (see Fig. 2b). To split bunches 

in three parts in one step, three different RF 

harmonics, h = 7, 14 and 21 are applied 

simultaneously to the beam. The intermediate RF 

component at h = 14 assures a splitting into three 

equal bunches. 

Fig. 2 (a) Double splitting and (b) Rebucketing 

A mountain range plot of 2 nd injection and triple 

splitting, measured on the PS flat-bottom, is shown 

in Fig. 3. Having now 18 bunches in harmonic 21 

the beam is accelerated to 26 GeV, its final energy in 

PS. Each bunch is then split in two on the flat top, 

changing the harmonic from 21 to 42, a mountain 

range plot is shown in Fig. 4. Effectively each of the 

injected bunches is split by a factor of six. This 

result in a batch of 36 bunches spaced by 50 ns. 

Finally the bunches undergo a rebucketing from 

harmonic 42 to 84. 

Fig. 3 2 nd injection and triple splitting 

Fig. 4 Double splitting with subsequent rebucketing 

Just before extraction the 36 bunches are drastically 

shortened to a bunch length of about 4 ns in order to 

fit into the 5 ns long RF-buckets (200 MHz) in the 

SPS. This is achieved by a sudden increase of the 

RF-Voltage at harmonic 84, which introduces a 

longitudinal bunch rotation in the RF-bucket. To 

further increase the RF voltage gradient, additional 

cavities at harmonic 168 are switched on during the 

last part of this rotation. When the bunches are 

shortest, the batch is ejected into the transfer line 

towards SPS. Up to four of these batches can be 

accumulated in one SPS cycle prior to their 

acceleration and following transfer to the LHC. 

Another important task of the PS is preserving the 

beam quality delivered by the booster. The quality of 

the beam is expressed by its longitudinal and 

transverse emittances, important measures of 

particle density. 

A certain emittance increase (blow up) is difficult to 

avoid and sometimes even necessary in order to 

stabilize the beam. A longitudinal blow up can for 

example ease a splitting process, when done in a 

controlled way. 

The transverse emittance should however be 

conserved as well as possible throughout the injector 

chain. A possible source of blow up may be for 

example coherent transverse injection oscillations. 

The bunches are then oscillating transversally 

around the ideal orbit due to a not perfectly aligned 

beam trajectory at injection. Also non-perfect 

working point settings can produce resonances, 

especially with very bright beams like the LHC 

beams. Both cases finally lead to filamentation of 

the beam, translating into a transverse emittance 

increase. 

In order to detect subtle changes more quickly the 

LHC beam quality is validated during each shift in 

all the injectors. 

Christoph Kittel, BE-OP-PS 


Beta Beams for neutrino physics 

at CERN 

CERN has a long experience in developing and 

running neutrino beams. S. van der Meer invented 

the idea of the magnetic horn, successfully used in 

most neutrino beam facilities worldwide to optimize 

the neutrino flux towards the detector. The “CERN 

Neutrinos to Gran Sasso” (CNGS) facility has been 

running since 2006. New proposals are emerging to 

pursue the exploration of the neutrino at CERN. The 

result of the 4-year FP7 study “EUROnu” 

(http://euronu.org) of three neutrino facilities, a 

Neutrino Factory, a Beta Beam and a so-called 

Super Beam, is now being published in the EUROnu 

final report and in an upcoming special issue of the 

journal PRSTAB. The costing of the facilities 

supposes they are built at CERN, which in practice 

means that similar costing methods are applied. 

CERN was leading the work package studying the 

Beta Beam. 

Neutrino oscillation arises from a mixture between 

the flavor and mass eigenstates of neutrinos. The 

three neutrino states (electron, muon and tau 

neutrino) are each a different superposition of the 

three neutrino states of definite mass. Neutrinos are 

created in their flavor eigenstates. As a neutrino 

propagates through space, the quantum mechanical 

phases of the three mass states advance at slightly 

different rates due to the slight differences in the 

neutrino masses. This results in a change of the 

relative phase of the mass states and therefore a 

different mixture of flavor states as the neutrino 

travels. The mixture of mass eigenstates (amplitude 

squared) remains the same; only the way they 

interfere gives the flavor oscillations. So, a neutrino 

born as, say, an electron neutrino, νe , will be some 

mixture of electron, muon, and tau neutrino after 

traveling some distance. Observation of how these 

changes in flavor state evolve gives information 

about how the transformation between mass and 

flavor eigenstates is governed, for example, if these 

oscillations are the same for neutrinos and antineutrinos 

(in vacuum). If they are not, we may 

observe charge and parity (CP) violation. We should 

remember, that in the Standard Model of physics, 

neutrinos are mass less; the fact that they oscillate 

shows that they have mass; this means that we 

witness physics beyond the Standard Model. 

Recently, the last missing mixing parameter θ13 (the 

parameter controlling the amplitude of νe oscillations 

at 500 km for a νe having an energy of 1 GeV) was 

found to be non-zero and large. This result now 

opens the possibility to access CP violation in the 

lepton sector. The Beta Beam has good potential for 

this measurement. 

The idea of a Beta Beam (BB) facility is to 

accelerate beta active isotopes to high energies and 

accumulate them in a storage ring, the Decay Ring 

(DR), see Fig. 1. To implement a BB at CERN, 

permits to profit of existing machines and the CERN 

infrastructure to limit the cost of the facility. 

However, the machines are not built for Beta Beams, 

this implies that studies of the existing machines and 

necessary modifications are part of the project. What 

is drawn in red in Fig. 1 are new equipment needed 

for the BB: targets for isotope production, an ion 

Linac, a Rapid Cycling Synchrotron, RCS, (work by 

IPNO, CNRS/IN2P3) and the large race track 

shaped DR (designed by CEA Saclay). In this ring, 

the radioactive isotopes decay to give neutrinos at 

the end of the straight sections, of which the one 

pointing to the detector gives useful neutrinos; the 

DR is tilted with a small angle, so that the neutrino 

beam reaches the detector; it has to traverse the earth 

since the distance to the detector is large (hundreds 

of kilometers). 

Figure 1: The Beta Beam at CERN. 

When beta active isotopes decay, they send out a 

neutrino with a well-known energy spectrum. This 

neutrino energy is further boosted forward by the 

well-known energy of the accelerated isotope. The 

advantage of a BB facility, compared to neutrino 

facilities using neutrinos coming from the decay of 

particles created by a proton beam on a target, is that 

the neutrino beam is a pure νe beam (there is no 

contamination of other neutrino types) and that the 

energy spectrum is well known. This makes the 

detection and analysis of the very rare neutrino 

reactions in the detector easier. 


One of the challenges for the BB is the production of 

the radioactive isotopes. They have to have suitable 

life times and suitable energy when they decay, to 

give the necessary rate of decays and have the right 

energy along the straight sections pointing to the 

detector. They also have to come in pairs, producing 

anti-neutrinos (β - emitter) and neutrinos (β + emitter) 

respectively. The EUROnu project has investigated 

the use of a small production ring to produce 8 B and 

8 Li in an internal target, which also serves as a 

stripper and an absorber for ionization cooling as 

shown in Fig. 3. Production rates achieved in 

simulations do not yet give the required rates for this 

option. However, an experiment during summer 

2012 at ISOLDE indicates that we may reach 

sufficient production of another isotope for the BB, 

18 Ne, using a molten salt loop target (Fig. 2). 6 He can 

be produced using conventional ISOL technology. 

Figure 2: The molten salt loop experiment at 

ISOLDE. 

Today’s baseline is therefore to use the pair 18 Ne and 

6 He for the production of neutrinos and antineutrinos 

respectively, using an upgraded Linac4 or 

a new Superconducting Proton Linac (SPL) as 

proton driver (see Fig. 1). A pulsed 60 GHz ECR 

source, for the first step to collect and ionize the 

isotopes coming from the production target, has 

been developed at the Laboratoire de Physique 

Subatomique et de Cosmologie, Grenoble (LPSC) 

and a prototype is constructed for the BB (tests 

during 2012). 

The injection into the DR, where a beam is already 

circulating, requires a technologically advanced RFsystem, 

however this is one of the challenges that 

may be relaxed now by the fact that the parameter 

θ13 has been found to have a large value. This is also 

true for the callenging stabilization of the high 

intensity ion beam in the DR, respectively 10 14 6 He 

ions and 7.4 ⋅ 10 13 18 Ne ions in 20 bunches. 

Collective effects in the existing CERN machines 

and decay losses (radiation protection, vacuum and 

power-deposition in accelerator equipment) have 

been addressed. No showstoppers have been found, 

however, more research is needed to consolidate and 

improve the results achieved. The EUROnu 

consortium has made a proposal to the European 

Strategy for Particle Physics: a combination of a 

Super Beam and a Beta Beam at CERN gives 

competitive physics reach. This has to be evaluated 

together with several other proposals, taking into 

account many factors and constraints like price, 

timing, other physics etc. 

Elena Wildner, BE-ABP-ICE 

CLIC through the eyes of art 

students 

The CLIC Conceptual Design Report (CDR) 

summarizes the concept of a Linear Collider based 

on the CLIC technology, its physics case and the 

expected performance and design of the physics. 

The accelerator part; entitled “A Multi-TeV Linear 

Collider based on CLIC Technology” has just been 

published as CERN-2012-007 (the other two parts 

were already been published as CERN-2012-003 

and CERN-2012-005). 

If you look inside the 850 page document you will 

see something a little bit different from other CERN 

reports. The images at the beginning of each chapter 

in the CDR are the result of a successful 

collaboration between the CLIC Project and the Art 

Department at La Chataigneraie International School 

in Founex (near Geneva). Following a visit to the 

school campus by Hermann Schmickler and myself 

in 2010, where the CLIC project was presented, 

students, aged from 15 to 17 years were invited to 

come up with their own visions of CLIC. In total, 

some 40 students took part in the project and 

submitted their artwork. It had been agreed with the 

school that this project would form part of their 

coursework and would count towards their final 

marks. 

As recognition of the effort put in by the students, 

and also to expose their work a larger audience, an 

exhibition was held in CERN's Main Building on the 


evening of Monday 6 th December 2010. Most of the 

students who had produced artwork were able to 

attend. The event took the form of a Vernissage but 

owed more to a typical poster session as an 

accelerator conference. The students were “on duty” 

in front of their oeuvres where they met and were 

more than happy to explain the motivation and ideas 

behind their work to the many CLIC collaborators 

who came along. 

Initially we had imagined using one of the students’ 

submissions on the front cover of the CDR, but in 

the end we decided to have a fairly traditional front 

cover as the report would be published as a CERN 

“Yellow Report” The editorial team selected 

amongst these contributions ten samples and 

inserted those at the beginning of each chapter. 

Since not all contributions could be used as part of 

the CDR, below we created an appendix in the 

document which displayed small thumbnails of all 

the contributions. 

My personal favorite, is shown here 

Here I include the personal account of three students 

(Fiona Teeling, Marissa Nordentoft and Edna 

Dualeh -year 11 students at the time) which shows 

that this was quite a special event. 

“After a long day of school, and a rather short car 

ride we made it to CERN. We collected our access 

badges, and followed a black line along the floor. It 

went on for a long time, and eventually became like 

a never ending `yellow brick road.' 

Once we finally found our way through the labyrinth 

of offices and formula-covered blackboards, a large 

white room opened before us. It was Monday 

evening (the 6th of December 2010) and we had 

finally arrived at the CLIC (Compact Linear 

Collider) exhibition. 

We were all very excited to see our artwork (more 

like masterpieces!) created by IGCSE and some IB 

students at the start of this school year, following a 

presentation at school by CERN physicists about a 

new linear collider project called CLIC. All of the 

students' artwork was presented on their own 

individual board. We all felt like we were part of 

something special, as we were standing on such a 

well-known and respected place. 

We got to meet a lot of important and influential 

people who were in charge of the CLIC project, or 

involved with CERN in one way or another. These 

scientists were from all over the world. They were 

nothing like the stereotypical scientists wearing 

white labs coats with mad hair like Einstein! 

It was a bit scary at first when they approached us to 

ask us about our artwork, as they are such important 

people, but we eventually got the hang of it. We got 

to explain to them the whole idea behind our final 

piece, and what it means to us. They gave us 

feedback and praised us for our good work. Being 

acknowledged for our work was worth all the time 

we had dedicated to the project. We learned that 

three winning pieces would probably be chosen as 

cover pages for the volumes of the CLIC conceptual 

design report, but also that all the artwork will 

probably appear in the report as chapter dividers. 

What an exciting opportunity for the school and us 

students! 

Monday the 6 th of December was more than a pat on 

the back. It was a day we will never forget, and 

hopefully we will get to meet them again. Now we 

can only wait in suspense for their selection of the 

winner(s).” 

You can consult the CDR at http://project-cliccdr.web.cern.ch/project-CLIC-CDR/ 

If you would like a printed copy, please use the 

order form here: 

https://indico.cern.ch/confRegistrationFormDisplay. 

py/display?confId=206903 

(Deadline: 20 December 2012) 

Mick Draper, BE-CO 


ACAS from the land Down Under 

– or – How I stopped worrying and 

started loving Vegemite 1 

CERN is expanding beyond Europe and becoming a 

truly global organization, embracing not only 

cultural and scientific diversity but also bridging the 

distance between the Antipodes of Switzerland and 

Australia. My relationship with the Australian 

Collaboration for Accelerator Science (ACAS) 

started in 2007, when as travelling spouse in 

Melbourne, I took the opportunity of reaching out to 

colleagues at the Australian Synchrotron and 

University of Melbourne that I had met during 

earlier conferences. The collaboration continued 

and was eventually formalized in 2010. 

ACAS provides a platform to coordinate Australia’s 

national research priorities with an emphasis on 

developing the accelerator-based research and 

technology sector through providing university-level 

training networks, capitalizing the investment in 

accelerator-based user facilities and fostering 

collaborations within and outside Australia such as 

CERN [1]. 

Melbourne – home of the Australian Synchrotron 

Light Source (ASLS) – also hosted this year's 

International Conference on High-Energy Physics 

(ICHEP'12) that brought physicists together to share 

their findings, deepen existing collaborations and 

celebrate the discovery of a new Boson compatible 

with the standard model Englert-Brout-Higgs 

mechanism. Australia has and is continuing to make 

valuable contributions to CERN's research and 

development programme, in particular related to the 

ATLAS data analysis, accelerator optics designs and 

measurement for future linear colliders, as well as 

collaborating with CERN's Beam Instrumentation 

Group. 

To improve the understanding of the Higgs and 

other new particles, a larger number of particle 

collisions and even higher beam intensities are 

needed, that are injected, accelerated and stored in 

the CERN accelerators. This intensity is 

1 Vegemite – a highly addictive vegetable based substance 

used as a bread-spread, while providing a very unique 

flavour incompatible with the palate of most Europeans, 

became one of my favourite acquired tastes and alongside 

some other unique Aussie idiosyncrasies such as an 

appreciation of 'footie' (Australian-Rule-Football), idioms 

and accents of my 'mates' became part not only of my 

private but also work life. 

fundamentally limited by self-amplifying beam 

instabilities, intrinsic to unavoidable imperfections 

in accelerators. The CERN-ACAS groups are 

collaborating on inventing novel beam 

instrumentation devices which aim to improve the 

diagnostics needed to better understand, and 

eventually cure these instabilities. 

ACAS actively encourages, supports and sends 

many PhD, Masters and summer students to CERN 

every year. Two of the students that have been 

recently sent through ACAS to work with the CERN 

Beam Instrumentation Group were Sophie Dawson 

and Tom Lucas. Sophie graduated with her research 

on an ultra-wide-band beam position monitoring 

using synchrotron light. The LHC operates at such 

high energies that it emits a significant amount of 

light that can be used as a diagnostic tool. The set-up 

used at CERN is based on earlier research at the 

ASLS and uses fibre-coupled, high-speed Metal- 

Semiconductor-Metal Photo-detectors in a custom 

balanced RF biasing circuit [2, 3]. 

CERN Director-General Rolf Heuer and CERN 

Research Director Sergio Bertolucci visiting the 

experiments and ACAS-CERN summer students at 

the ASLS in Melbourne. front: Kent Wootton (2008), Tessa 

Charles (2009), Rolf Heuer (CERN DG), Sophie Dawson (2010), 

Sergio Bertolucci (CERN DS), David Peake (2007).back: Mark 

Boland (ACAS & ASLS), Ralph Steinhagen (CERN BE-BI), 

Roger Rassool (ACAS Director & Uni-Melbourne). not in the 

photo: David Ogburn (2011), Tom Lucas (2012). 

The ASLS was used as a test-bed because the 

characteristics of the generated light are in many 

ways very similar to LHC, but importantly it is more 

accessible during regular operation than at the LHC. 

The time window around ICHEP'12 was thus also 

used to advance the experiments at the ASLS which, 

along with former CERN summer students, has been 

visited by CERN’s Director-General Rolf Heuer and 

Director for Research Sergio Bertolucci. 

Tom Lucas worked on a project that aims at 

improving the resolution of the signal-processing 


chain connected to the synchrotron-light or any other 

high-bandwidth beam position pick-up, nicely 

complementing Sophie's studies. Traditionally, intrabunch 

or head-tail particle motion is measured in 

time-domain using fast digitizers operating at speeds 

of 20 GHz or above to resolve oscillations in the less 

than 1 nano-second short particle bunches. However, 

at these speeds, the effective resolution of even 

state-of-the-art technology limits the effective intrabunch 

position resolution to about 100 μm. At the 

LHC, beam particle oscillations at this scale – 

outside of special machine development studies – 

cause partial or a total loss of the beam due to the 

tight constraints imposed on transverse oscillations 

by the LHC collimation system to protect LHC's 

sensitive cryogenic aperture. 

To improve on the present signal processing, Tom 

designed, constructed and performed prototype tests 

at the SPS and LHC using a new alternate, 

frequency-domain based diagnostics approach: his 

system splits the beam signal into multiple equallyspaced 

narrow frequency bands that are processed 

and analyzed in parallel using RF Schottky diode 

peak detectors. While the information content is 

equivalent to working in time-domain, working with 

narrow-band signals in frequency-domain permits 

the use of much higher resolution analogue-todigital-converters 

that can be used to resolve nanometer-scale 

particle oscillation amplitudes already 

during the onset of instabilities. This enables the 

precise beam parameter measurement under still safe 

conditions; and will eventually help to define the 

machine parameters that are effective to mitigate 

these instabilities before they become critical. 

The system is also being evaluated at the ASLS that 

has much shorter bunch lengths, which makes direct 

time-domain signal-processing even more 

challenging and provides a worthy proofing ground 

for the system's diagnostic principle in general. 

The collaboration between CERN and ACAS has 

always been very active and productive with a 

welcoming atmosphere, with ACAS striving to walk 

the extra mile necessary to overcome the tyranny of 

distance and difference in time-zone. We are looking 

forward to continuing working with our Australian 

colleagues and hope that there will be many more in 

the future at CERN. 

ACAS provides not only an important contribution 

to the advancement of science and technology in 

Australia and CERN but possibly also the stepping 

stone for advancing the relationship between these 

two organizations. Australia greatly values the 

relationship with CERN and the opportunities that it 

provides and is keen to continue to contribute to the 

global effort in high-energy physics and related 

technology R&D required for the discovery of new 

Physics. In recognition of this exciting window of 

opportunity that has opened up, ACAS is developing 

plans and a strategy for Australia to become an 

associate member of CERN. 

References: 

[1] http://accelerators.org.au 

[2] D.J. Peake et al, NIMAA 589 (2008) 

[3] S. Dawson et al. IBIC'12, 2012 

Correspondents: 

Newsletter Contacts 

Ralph J. Steinhagen, BE-BI 

ABP G. Arduini & H. Mainaud Durand 

ASR C.–E. Sala 

BI E. B. Holzer 

CO M. Draper 

OP C. Kittel 

RF W. Höfle 

Copy Editor L. Van Cauter-Tanner 

Design Editor E. Gavriil 

Editor-In-Chief R. Billen 


Colonne Sécurité 

Produits chimiques : nouveaux 

symboles, mêmes dangers ! 

Un nouveau système d’étiquetage harmonisé est en 

train de se mettre en place. Il s’agit de symboles 

noirs sur fond blanc bordés de rouge. Ces symboles 

seront pleinement en vigueur dans tous les pays en 

2017. 

Centre anti-poison 24h/24 

Suisse – 145 

France – 04 72 11 69 11 

CERN, Brigade du feu 74444 

Appel d’urgence Européen : 112 

Pour plus d’informations : 

* Rendez-vous sur le site cheminfo.ch. Un test en 

ligne, plus orienté maison est accessible et 

permet de se poser les bonnes questions….même 

au travail. 

* Nous tenons à votre disposition des dépliants 

« Nouveaux symboles, mêmes dangers » édités 

par la Confédération Suisse et infochim.ch. 

N’hésitez pas à nous contacter si besoin, 

Unité de Sécurité BE 

Envoyer un message 

Safety Column 

Chemicals : new signs, same 

dangers! 

A new harmonized international labeling system is 

being put in place. Signs will be back on a white 

background bordered in red. These symbols will be 

fully implemented in all countries in 2017. 

Poison control center 24h/24 

Switzerland – 145 

France – 04 72 11 69 11 

CERN, Fire Brigade 74444 

European Emergency call: 112 

More information: 

* Visit the web site cheminfo.ch. An online test on 

household risks can be filled in and enables you 

to ask yourselves the right questions… even at 

work. 

* We keep at your disposal some flyers 

« Nouveaux symboles, mêmes dangers » 

published by the Swiss Confederation and 

infochim.ch. 

Do not hesitate to contact us, 

BE Safety Unit 

Send a message

Newsletter - Cern

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