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An overview of CERN Antiproton facility in the Eighties & Nineties : i.e., what was done & happened at CERN in the AA  (1980 onwards) and later on in the AA+AC era (1987 onwards) till the closure in 1996 and re-starting 3 years later in AD. V. Chohan CERN.

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V. Chohan CERN

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V chohan cern

An overview of CERN Antiproton facility in the Eighties & Nineties : i.e., what was done & happened at CERN in the AA  (1980 onwards) and later on in the AA+AC era (1987 onwards) till the closure in 1996 and re-starting 3 years later in AD

V. ChohanCERN

[email protected] Workshop

GSI, Darmstadt 3-4 Dec 2007


The cern antiproton operation 1980 83

The CERN Antiproton Operation- 1980-83

[email protected] Workshop

GSI, Darmstadt 3-4 Dec 2007


The antiproton machines after isr closure but with lear 1983 onwards aac 1987 onwards

The Antiproton Machines after ISR closure but with LEAR (1983 onwards )& AAC (1987 onwards)

[email protected] Workshop

GSI, Darmstadt 3-4 Dec 2007


V chohan cern

[email protected] Workshop

GSI, Darmstadt 3-4 Dec 2007


Some generalities

Some Generalities

  • The p-pbar Collider Physics at UA1, UA2 was the ‘raison d’etre’

  • The whole Laboratory was involved in this ‘adventure’ into the unknown

  • From the day production started ~ end 1980, we discovered that our overall pbar yields were rather low, much lower than expected . The AA machine had many limitations including Acceptances, cooling systems’ interplay and limits ( ‘combined functionalities’ , shutters ) and so forth.

  • Hence the Quest was for producing & storing more Antiprotons from 1981 onwards

  • The talk specifically excludes issues of machine & stochastic cooling systems design because it is well documented elsewhere

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GSI, Darmstadt 3-4 Dec 2007


Broad outline of the talk

Broad Outline of the Talk

  • AA and What it was

  • AC Design & AAC

  • Towards the AAC: Machine & Production

  • R & D on Collectors & Production

    • Conducting Target

    • Li lens

    • Improved Horn

    • Consolidation of Passive Target

    • { Plasma lens }

  • Constraints at Start up in 1987 & ‘ Abandoned ‘ issues

  • AAC Operation at Peak Performance for p-pbar Collider ( ‘89-’90)

  • AAC Performance Issues for a Complex of Several Machines

    Abandoned hopes for the top-Quark at CERN

  • AAC Op. for Collider Low Luminosity run ’91 ( precursor of LHC- TOTEM)

  • AAC Operation for steady-state LEAR runs ’92-96

  • Some Issues for Operational robustness, reliability ?

  • [email protected] Workshop

    GSI, Darmstadt 3-4 Dec 2007


    Overview 1980 1987

    Overview 1980-1987

    • What was the AA – Single Ring

      Limitations In AA

    • Design of AC Ring

      Expectations of the AAC complex

      ( AA +AC concentric Rings)

    • Design Goals & Collector Lenses

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    GSI, Darmstadt 3-4 Dec 2007


    The antiproton accumulator

    The Antiproton Accumulator

    • Machine was constructed 1978-1980 as an “Experiment”

    • The UA1 & UA2 were the first Large collaborations and the pioneering pre-cursors to large LEP Expts. & present LHC Expts.

    • Machine Design was for 100π Transverse Acceptance 1.5 % in Δp

      Achieved only ~ 80 πin both transverse planes

    • Copper Target & Magnetic Horn for pbar collection

      first target was tungsten but was soon replaced by Cu for better yields

      Operational Yield ( pbars per proton) on Inj Orbit ~ 5E-7

      Best Accum. Rate ~ 6 E9 /hr

    • Several Stochastic cooling systems ( pre-cooling, Stack tail & Core )& multi-functionality within same ring needing pulsed Shutters, interference of systems & limitations in stack Core size

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    GSI, Darmstadt 3-4 Dec 2007


    1981 first yields and missing factor

    1981 First Yields and “ MISSING FACTOR “

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    GSI, Darmstadt 3-4 Dec 2007


    The aa before ac the continued struggle for chasing the missing factor 1986

    The AA before AC & the continued struggle for chasing the “ Missing Factor ” (1986 )

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    GSI, Darmstadt 3-4 Dec 2007


    Towards the design of the cern ac ring 1982 83 84 ad aa @fnal too

    Towards the Design of the CERN AC Ring ( 1982-83-84 )& [AD+AA]@FNAL too !

    Aim to Increase the Stacking Rate by a factor 10

    and hence provide a bigger flux for the Collider Operation ( LEAR was only a ‘parasitic’ operation )

    How?

    Have a Separate Ring( AC-Antiproton Collector) separate some functions ( fast pre-collect , debunch & fast pre-cool ) and use AA purely for Stack Core Accumulation

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    GSI, Darmstadt 3-4 Dec 2007


    How was the factor 10 in stacking rate to be achieved

    How Was the Factor 10 in Stacking Rate to be Achieved ?

    AC Ring Design

    • Transverse Acceptance Design : 240 π in both H & V

      • So up on the AA ( Design was 100 π both planes) by aFACTOR 4

        AC design was for 240π for a simple reason, since AA only achieved 80π i.e., 20 % less than Design 100π, we DESIGNED AC for 20 % more, to achieve 200 π in REALITY !

    • Longitudinal Acceptance 6 % ( AA was 1.5 %)

      • So up on the AA by a Factor 4

    • Total Expectation of a GAIN by a factor 4 x 4 = 16 in Pbars Acceptance

    • For the same Production Beam Repetition rate (every 2.4s = 1500 shots per hour), this increased transverse & longitud. Phase space necessitated a re-designed Pbar production target system to provide the increased yield & to populate this phase space; this gave an expectation in increased pbar flux or an Accumulation Rate increase of at least factor 10, ie.,

      6 E6 → 60 E6 pbars per PS Prod. Beam Shot

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    GSI, Darmstadt 3-4 Dec 2007


    Greater than factor of 16 in production meant what

    Greater thanFactor of 16 in Production meant what ?

    • Even if we had an increased number per shot arriving on the Inj. Orbit in AC by a factor 16 , i.e.,

      6E6 ( as was on AA Inj orbit ) x 16 = ~ 100E6 ( in AC )

    • For the whole chain from Inj in AC to final store in AA only a 50% efficiency was considered as reasonable, meaning

      50E6 x 1500 cycles per hr. ( in 2.4 sec PS Production cycles),

      = 7.5 E10 pbars per hr.

      so largely meeting the physics aim of having factor 10 in stacking rate per hour from

      6E9 in AA to 6E10 in the AAC complex

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    GSI, Darmstadt 3-4 Dec 2007


    Factor 16 in acceptance and its filling

    Factor 16 in Acceptance and its Filling

    • To fill 16 times bigger machine acceptance also needed at least a factor 16 in the Pbar Production at the target.

    • The Development of new Cylindrical ‘Magnetic lenses’ focussing in both or all planes straight after the target was started already in early 1982 after “discovering” that at least a factor 5 was missing in the AA Production &/or Accumulation rate ; Such lenses reduce the ‘collecting’ angles by at least 10 compared to normal Quadrupoles.

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    GSI, Darmstadt 3-4 Dec 2007


    Quest for more pbars expected yield gains in ac over aa for different targets collector lenses

    Quest for more pbars & Expected Yield Gains in AC over AAfor Different Targets & Collector Lenses

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    GSI, Darmstadt 3-4 Dec 2007


    Development of new targets collection lenses

    Development of New Targets & Collection Lenses

    The R & D was on various fronts:

    • Lab tests of a conducting target +horn assembly pulsed at 200 kA , 30 µs pulse followed by Machine Testsof theConducting Target and Yield evaluation

    • Further development of “wire lenses” , meaning the wire conductor is a cylindrical rod ofLithium contained inside a steel or titanium shell

      ( Novosibirsk & FNAL ideas & development)

    • Improvement of the “current-carrying” sheet CERN design(1962)Magnetic Horn used already in AA but with larger current and collection angles

    • ‘plasma Lens’ R & D was also envisaged

    • Consolidation & Improvement of Passive Targets

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    GSI, Darmstadt 3-4 Dec 2007


    Pulsed conducting targets subject seems reactivated today for neutrinos

    Pulsed Conducting Targets : ( subject seems reactivated today for neutrinos )

    • Advantages:

      • Large Collection Angle implying Greater number of particles within a given Acceptance

    • Drawbacks

      • Larger the collection angle, stronger the collector lens needed DOWNSTREAM of the target

      • The field that focuses the antiprotons de-focuses the protons and this effect must be taken into account and imply putting an extra pulsed focusing lens on the proton beam BEFORE the target

      • Many particles forced to traverse the target & re-absorption is relatively high

      • Long Testing Periods in laboratory to evaluate mechanical issues

      • Further Durability issues to be considered under repeated ‘shocks’ of proton beams

      • Highly radioactive zone making repair/replace conditions very difficult

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    GSI, Darmstadt 3-4 Dec 2007


    Pulsed conducting targets development

    Pulsed Conducting Targets Development

    • Laboratory Tests :

      • Connecting Horn in series with Target (3 mm dia.) and pulsing at 200 kA , 30 us pulse to permit sufficient field penetration

      • Lab. Tests were all Destructive

      • Container lifetime problems & technological challenges

    • Machine Tests

      • THREE Experiments were carried out

      • Higher Yields ( >50 % more) were observed

      • Very limited lifetime of the target – few hours due to fracturing of the device

      • Beam Induced Effects - problems due to maximum of current (140 uA) being at the same time as proton beam releasing energy in the target ( high temperature rise), resulting stresses & shock effects

      • Technological problems of stress , fatigue in target containers

      • Thermal cooling using gas

    • Some Lessons from Tests & further development directions

      • Reduce the stresses by decrease in current or increase in target diameter, etc..

      • Highly radioactive target meant very difficult repair & replacement ; if frequent target exchanges were necessary, a rapid exchange using remote-handling capability was needed for the target area ( new Target Area Design)

      • Separation of Pulsers – one each for horn & Conducting target

      • Study liquid metal targets.. [ in vogue again now (2007) …!! For neutrinos…..]

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    GSI, Darmstadt 3-4 Dec 2007


    Conducting target first ideas 1982

    Conducting Target – first ideas 1982

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    GSI, Darmstadt 3-4 Dec 2007


    Conducting target yield expectations

    Conducting Target : Yield Expectations

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    GSI, Darmstadt 3-4 Dec 2007


    Proton pre focus li lens pulsed conducting target pulsed magnetic horn as pbar collector

    Proton Pre-Focus Li Lens, pulsed Conducting Target, pulsed Magnetic Horn as pbar Collector

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    GSI, Darmstadt 3-4 Dec 2007


    Development of lithium lens

    Development of Lithium Lens

    • Original Novosibirsk Development, taken further for Pbar Source at Fermilab in early eighties.

    • Water Cooling was used in Li lens assembly

    • At Fermilab, problems overcome with :

      • sufficient spares of targets & Li lenses,

      • a new, well designed target area with quick replacement , exchange possibilities ( unlike at CERN where we already had AA running with the original target area based on the concept of AA being a one-off experiment !)

    • Work on 20 mm Li Lens with pulser of up to 625 kA in lab and somewhat less ( 450 kA ) in the machine

    • Work on 36 mm Li Lens to operate at 1.3 MA with a pulser delivering up to 1.5 MA

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    GSI, Darmstadt 3-4 Dec 2007


    Li lens instead of magnetic horn for higher yields first ideas

    Li Lens instead of Magnetic Horn for higher yields – First Ideas

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    GSI, Darmstadt 3-4 Dec 2007


    Water cooled 36 mm li lens assembly

    Water cooled 36 mm Li Lens Assembly

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    GSI, Darmstadt 3-4 Dec 2007


    Some problems drawbacks of lithium lens

    Some Problems & Drawbacks of Lithium Lens

    • 36 mm lens did indeed have larger yields over 20 mm one BUT ONLY for large value of current ( > 1.1 MA )

    • Water Leak problems and issues of repair in radioactive area

    • Life tests in lab again gave container problems with the stainless steel container and this had to be INCREASED at the expense ofREDUCING the Li diameter from 36 mm to 34 mm– however this reduced the effectiveness of cooling and consequentlylimited the max . Permissible current to about 1 MA – else Li would partially melt; however now, it meant that the yield gain over 20 mm Li lens was very small ~ 7 %and the only way was to go to Liquid Li and develop a new cooling system !

    • High Current Pulsers Need and Development Costs

      & finally, 1989/90 runs had shown that Top Quark limit was beyond the 315 GeV on 315 GeV collisions at SPS Collider & 980-980 GeV FNAL had an open field for them - so

      nobody would want to finance new R&D on Li lenses - and LEP had already started!!

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    GSI, Darmstadt 3-4 Dec 2007


    Yields vs intensity different collectors last cern results

    Yields vs Intensity : Different Collectors ( last CERN Results )

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    GSI, Darmstadt 3-4 Dec 2007


    Subject not complete without talking of robustness of passive targets

    Subject not complete without talking of Robustness of Passive Targets

    • Problems of Target Fracturing, loss of Yield in early AA operation

    • Damaged but highly radioactive Targets were sliced /analysed in EIR-CH( now PSI) & in Seibersdorf – Austria

    • Lots of Work done on improving Targets

    • Final AAC start up in July 1987 used passive Irridium Targets in a unit of 3 pellets assembled together

      • Lots of References – Terry Eaton et al

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    GSI, Darmstadt 3-4 Dec 2007


    Aa shutdown for ac installation aac startup for physics

    AA Shutdown for AC installation & AAC Startup for Physics

    • Only Nine month shutdown to install AC ( Aug86-July87)

    • Competition with FNAL was still on – race for the discovery of the Top Quark & having UA1 + UA2 running with p-pbars again as fast as possible

      { problems in UA1 Detector + Rubbia as DG 1989 issue came after }

    • Difficulties in manning & funding R & D – especially to test in beam conditions and at the same time providing operational facility for physics meant that AAC started with options of :

      • smaller 20 mm dia. Li lens &

      • 60 mm Horn as a backup

        that is, No Conducting Target, hence no proton Focus Li lens either

    • No 36 mm Li Lens

    [email protected] Workshop

    GSI, Darmstadt 3-4 Dec 2007


    Aac startup injection line matching

    AAC Startup & Injection Line Matching

    • However, the Injection Line from the Target+ Collector lens to the AC Ring was DESIGNED for Matching the 36mm Li lens to the AC ring with 240π Transverse Acceptance and 6 % Momentum Acceptance

    • So by now using a 20 mm Li lens or Horn, this Matching was no more valid to transmit 240 π acceptance ; only about 200 π Acceptance was possible, after modifying the matching conditions. The radius of beam at exit of the collector lens was used as a variable parameter such that:

      R-acc = 15 mm for 20mm Li lens with α =0

      R-acc = 30 mm for 60mm Horn with α ≠ 0(tilted ellipse)

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    GSI, Darmstadt 3-4 Dec 2007


    Ac injection line matching isuues of 36 mm 20 mm li lenses 60 mm magnetic horn

    AC Injection Line Matching & Isuues of 36 mm, 20 mm Li Lenses & 60 mm Magnetic Horn

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    GSI, Darmstadt 3-4 Dec 2007


    20 mm li lens permitted only 200 acceptance

    20 mm Li Lens permitted only 200πAcceptance

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    GSI, Darmstadt 3-4 Dec 2007


    Aac startup injection line air scattering

    AAC Startup & Injection Line Air Scattering

    • Due to high level of induced radioactivity and maintenance difficulties for vacuum systems, large part of the dogleg up to the proton Dump are in the air as well as the antiproton Channel towards the AC (~15 m of beam line elements have no vacuum chamber )

    • The presence of air implies multiple Coulomb scattering and consequent beam loss ; the loss in yield due to air is of the order of up to 16 %

    • Several Modeling & Simulation programs to estimate yields : the origin from AA days had S.van der Meer’s program later on modified by Sherwood & Hancock for AAC and finally Nick Walker using Monte Carlo techniques

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    GSI, Darmstadt 3-4 Dec 2007


    Final results for p pbar collider operation 1988 1991 later only lear till 1996

    Final Results for p-pbar Collider Operation (1988-1991) & later only LEAR (till 1996)

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    GSI, Darmstadt 3-4 Dec 2007


    Yields operational performance comparisons

    Operational Yields with 1.5E13 Protons on Target ( CERN Experience)

    Yield defined as no. of Antiprotons on Inj Orbit in the AC Ring per Incident Proton on Target

    Yields & Operational Performance Comparisons

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    GSI, Darmstadt 3-4 Dec 2007


    Peak performance aac era sps lear both running

    Peak Performance AAC era: SPS & LEAR both running

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    GSI, Darmstadt 3-4 Dec 2007


    V chohan cern

    The interplay of multifarious systems to

    finally arrive at pbars stored in the stack in the AA

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    GSI, Darmstadt 3-4 Dec 2007


    Aac performance dependency factors final figure of merit

    AAC Performance & Dependency Factors : Final Figure of Merit

    Note:

    pbars per shot: > 71 E6

    Stacking rate: 53 E9/hr

    Accumulation Yield: ~ 44 E-7

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    GSI, Darmstadt 3-4 Dec 2007


    From aa to aa ac 1981 1991 stacking rates peak stacks

    From AA to [AA+AC] : 1981-1991Stacking Rates & Peak Stacks

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    GSI, Darmstadt 3-4 Dec 2007


    Sps collider peak performnce pbar transfers 1989 6 on 6 p pbar

    SPS Collider Peak Performnce pbar transfers – 1989 [ 6 on 6 p & pbar ]

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    GSI, Darmstadt 3-4 Dec 2007


    Last pbars sent to sps dec 1991 3 proton shots v s 3 antiproton shots

    Last Pbars sent to SPS [ Dec 1991 ] : 3 proton shots v.s 3 Antiproton shots

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    GSI, Darmstadt 3-4 Dec 2007


    Sending antiprotons both to sps lear 1991

    Sending Antiprotons both to SPS & LEAR (1991)

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    GSI, Darmstadt 3-4 Dec 2007


    Aac for sps collider lear 1987 91 to a single client lear 1992 96

    AAC for SPS Collider & LEAR {1987-91 } to a single -client LEAR {1992-96 }

    [email protected] Workshop

    GSI, Darmstadt 3-4 Dec 2007


    Ad example of recent times uses robust magnetic horn 1 4 mm thick

    AD Example of recent times: Uses Robust Magnetic Horn 1.4 mm thick

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    GSI, Darmstadt 3-4 Dec 2007


    Some lessons learnt

    Some Lessons Learnt

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    GSI, Darmstadt 3-4 Dec 2007


    Engineering of passive targets

    Engineering of Passive Targets

    • This is vast domain in its own right

    • Suffice to say that at CERN we went through the whole range of issues from Initial Copper Target of 1981 to what is used in AD today

    • Problems of Cu Target micro cavitation / fracture & loss in Yield

    • documentation exists, particularly for the period leading up to the AC Ring in 1987 and why we have now (for the AD) the Irridium Target Assembly in a unit of 3 pellets assembled together

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    GSI, Darmstadt 3-4 Dec 2007


    Antiproton production collection ensemble

    Antiproton Production & Collection Ensemble

    • The Collector lenses should not be disassociated from issues of antiproton production by hitting a target

    • Target assembly and associated issues need to be dealt with fully in a correctly engineered manner to lead to

      a properly designed “Target + Collector Area”

    • Lot of the early days of AA (1980-85) were spent in having target aspects being analyzed, consolidated, modified , improved etc to build up a store of engineering knowledge that one takes for granted today ( say, in AD running of today) . Some of these aspects were also related to AA being defined as an “experiment” only as well as due to the idea of developing ‘conducting ‘ targets.

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    GSI, Darmstadt 3-4 Dec 2007


    Robustness reliability issues

    Robustness, Reliability Issues

    ( Assuming that the machine and stochastic Cooling systems are all well designed

    from the wealth of experience at CERN & FNAL )

    Production depends on what one wants in terms of Reliability and associated Robustness

    • Production Area is implicitly highly Radioactive

    • Hence, one needs minimized repair and interventions as well as to have assured uptime

    • One must therefore consider:

      • Production Targets and Target Assembly Design

      • Collector Lens that go with the Target

      • Design of the Target Area consisting of the appropriately engineered issues of Targets, Cooling , high current pulsers and the powering of the Collectors in a radiation-hard manner in most general sense of the word

      • Separate Water Collection possibilities for Target Cooling circuits due to radiation

      • Facilitated Target or Collector replacement by Spares with easy-to-change procedures &/or remote handling and “cooling down” or storage zone for highly active, removed devices

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    GSI, Darmstadt 3-4 Dec 2007


    Production yields suitability of collectors

    Production Yields & Suitability of Collectors

    We Consider Essentially the TWO types of requirements where Antiprotons are produced and the solutions chosen:

    • High Production Yields & high energy Collider Needs

      • CERN during Collider days, FNAL even now

    • Reliable steady state Yields and Low Energy type of needs

      • LEAR

      • AD

      • GSI ??

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    GSI, Darmstadt 3-4 Dec 2007


    Magnetic horns

    Magnetic Horns

    • Horns were to become the preferred Solution for the AAC era for the single-client operation (LEAR) from 1992 onwards till the end of LEAR in 1996

    • Development of robustness

    • Development of sufficient spares

    • Conical to bi-conical shape permitted independence from adjustment of target distance from horn like in li lens operation optimisation

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    GSI, Darmstadt 3-4 Dec 2007


    Target magnetic horn assembly schematics

    Target & Magnetic Horn Assembly Schematics

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    GSI, Darmstadt 3-4 Dec 2007


    Magnetic horns advantages

    Magnetic Horns & Advantages

    • Horns have now become the preferred Solution for steady state , Reliable Operation. { e.g., the AAC era for the single-client operation (LEAR) from 1992 onwards till the end of LEAR in 1996 & now for the AD since 1998 }

    • Development of robustness

    • Relatively low-cost [ ~ 40 KCHF vs. ~200 KCHF Li Lens]

    • Ease in Availability of sufficient spares

    • Ease in Operation Use [ Conical to bi-conical shape permits independence from adjustment of target distance from horn like required in Li lens operation optimisation ]

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    GSI, Darmstadt 3-4 Dec 2007


    Magnetic horn steady state reliable operation

    Magnetic Horn & Steady-state , Reliable Operation

    • The 400 kA Horn used for LAST low-luminosity Collider run ( 3 on 3) was 1 mm thick and as the table shows, gave average yield of around 46 E-7 with 1.5 E13 protons on target

    • However, there were some mechanical problems, operating near fatigue limits and some recurring failures in 1991/1992

    • These problems and the need for LEAR only steady state Operation ( without Peak Performance in Production/collection/Storage) led us to Improve and consolidate the same horn BUT, with 1.4 mm thickness and Improved Cooling togive us a RELIABLE Device

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    GSI, Darmstadt 3-4 Dec 2007


    Reliable steady state horn based operation mar apr 1989 apr dec 1991

    Reliable, Steady State Horn based Operation { Mar-Apr 1989 & Apr-Dec 1991 }

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    GSI, Darmstadt 3-4 Dec 2007


    Li lens in routine operation yields 1989 ua2 1991 low luminosity

    Li Lens in Routine Operation & Yields: 1989 (UA2) & 1991 (low-Luminosity)

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    GSI, Darmstadt 3-4 Dec 2007


    Extra slides

    Extra Slides

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    GSI, Darmstadt 3-4 Dec 2007


    V chohan cern

    [email protected] Workshop

    GSI, Darmstadt 3-4 Dec 2007


    V chohan cern

    [email protected] Workshop

    GSI, Darmstadt 3-4 Dec 2007


    Table of parameters for comparison cern fnal

    Table of Parameters for comparison : CERN & FNAL

    4.6 E-6

    7 E+7

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    GSI, Darmstadt 3-4 Dec 2007


    Some references aa aac machines

    Some References : AA & AAC machines

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    GSI, Darmstadt 3-4 Dec 2007


    Some references conducting targets passive targets

    Some References :Conducting Targets, Passive Targets

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    GSI, Darmstadt 3-4 Dec 2007


    Yields vs intensity different collectors last cern results1

    Yields vs Intensity : Different Collectors ( last CERN Results )

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    GSI, Darmstadt 3-4 Dec 2007


    Collector lens for gsi

    Collector Lens for GSI ?

    • I would conclude that a Magnetic Horn would provide a better sustained and a reliable solution at a reasonable cost compared to Lithium Lenses

    • This conclusion assumes that regular changes of Li lenses like at Fermilab with dedicated & designed target zone and storage is not cheap

      [ However a correctly designed Target & collector zone would be a MUST too for GSI – at CERN we did not have that & suffered due to that]

    • Li lenses and their regular spares are much more expensive than Horns

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    GSI, Darmstadt 3-4 Dec 2007


    Target area issues

    Target Area Issues

    Attempt to deal with this in a general manner & considering :

    • Issues of Production & Collection Ensemble and what one must not forget if one wants a stable , reliable, steady state source of Antiprotons, nowadays for example for Low Energy AD Operation, i.e., Issues of:

      • Targets

      • Collectors

      • Target + Collector Area

    • Steady State Production Yields

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    GSI, Darmstadt 3-4 Dec 2007


    Some beam physics issues lest we forget 1

    Some Beam Physics Issues, lest we forget….(1)

    • In our world of MATTER, we need to make special efforts to create ANTIMATTER , or for that matter (sorry for the pun) ANTIPROTONS

    • PRIMARY PRODUCTION BEAM ISSUES

      • Incident beam as “bright” & focussed as possible to have pbar acceptance limits in the Collector lens satisfied as best as feasible because finally, the transverse size of the pbar beam is proportional to incident proton beam size – hence obligatory good focussing

      • Target : small diameter matched to incident beam diameter BUT should be long enough for all impinging beam to interact AND Short enough for maximum pbars to “escape” without re-absorption

      • Large Acceptance “Collector Lens” after the target

      • A matched Beam Transport Line after the “collector lens” to

      • A Large Acceptance “Collector Ring”

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    GSI, Darmstadt 3-4 Dec 2007


    Some beam physics issues lest we forget 2

    Some Beam Physics Issues, lest we forget….(2)

    • Drawbacks/disadvantages of higher energy primary beams ( compare CERN vs. FNAL)

      • Higher energy primary beam also means higher energy collector ring ( roughly 10 % so, CERN has a 3.5 GeV Collector Ring from the 26 GeV PS primary beam & FNAL has an 8 GeV Collector ring (called Debuncher) from the 120 GeV production beam)

      • Issues of higher acceptance as in CERN AC and difficulties of collection & “collector lens” chosen/required + associated high current pulser etc

      • Higher acceptance for Collector Ring implies added higher requirements on stochastic cooling systems

      • Higher energy dissipation on target for the same Temperature limits on the target material implies that intensity of beam has to be limited if target is not supposed to melt ; this therefore upper limited the intensity at CERN to ~ 2.5 E13 on target in the AAC era ( never exceeded ~1.7E13 ) & 5 E12 at FNAL pbar source; this limit is still the same in the CERN-AD era ;

      • Finally , if one compares CERN AC Ring & FNAL Debuncher Ring, the no of pbars on Inj. Orbit is roughly the same !! ( ~5E7 at CERN & ~7E7 at FNAL)

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    GSI, Darmstadt 3-4 Dec 2007


    Some beam physics issues lest we forget 3

    Some Beam Physics Issues, lest we forget….(3)

    • For the DENSE and INTENSE ANTIPROTON Beams at low Momentum ( 300 MeV/c down to 100 MeV/c), One Needs :

      • A high Energy, high Intensity Proton Synchrotron to provide the Primary Production Beam

      • A good Target (passive to be least complicated)

      • A good, robust, large acceptance pbar Collector lens after the target

      • A large Acceptance Collector Ring

      • Bunch Rotation, debunching , cooling and Deceleration to bring the Injected pbar flux down to Low Momentum and FURTHER cooling to improve Density at low momentum

    [email protected] Workshop

    GSI, Darmstadt 3-4 Dec 2007


    Yields summary hamburg intl high energy acclr confr 1992

    Yields Summary( Hamburg Intl High Energy Acclr Confr 1992 )

    [email protected] Workshop

    GSI, Darmstadt 3-4 Dec 2007


    V chohan cern

    [email protected] Workshop

    GSI, Darmstadt 3-4 Dec 2007


    V chohan cern

    [email protected] Workshop

    GSI, Darmstadt 3-4 Dec 2007


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