design note tri dn low energy beam transport line for the...

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Document-116897

Design Note TRI-DN-15-06

Low Energy Beam Transport Line for the CANREB Charge State Breeder

Document Type: Design Note

Release: 03 Release Date: 2016/09/09

Author(s): S. Saminathan & R. Baartman

Name:

APPROVAL RECORD

Author(s):

S. Saminathan

R. Baartman

Reviewed By: F. Ames

Approved By: R. Kruecken

Note: Before using a copy (electronic or printed) of this document you must ensure

that your copy is identical to the released document, which is stored on TRIUMF’s

document server.

https://documents.triumf.ca/docushare/dsweb/ServicesLib/Document-116897/Routing

Low Energy Beam Transport Line for the CANREB Charge State Breeder

Document-116897 Release No. 03 Release Date: 2016/09/09

2

History of Changes

Release

Number Date Description of Changes Author(s)

#01 2015-04-09 Initial Release S. Saminathan &

R. Baartman

#02 2015-06-29

Updates on Nier-spectrometer

optics by including DR

committee’s recommendations

S. Saminathan &

R. Baartman

#03 2016-09-09

Injection beamline optics has

been redesigned to accommodate

the pulsed drift

tube relocation. Also an update

on Nier-spectrometer optics.

S. Saminathan &

R. Baartman

Distribution:

Friedhelm Ames, Rick Baartman, Brad Barquest, Jose Crespo ([email protected]),

Jens Dilling, Eric Guetre, Rituparna Kanungo, Reiner Kruecken, Bob Laxdal, Dan Louie,

Marco Marchetto, Norman Muller, Matt Pearson, Asita Perera, Doug Preddy, Dan Rowbotham,

Michael Rowe, Victor Verzilov, Dimo Yosifov,

Keywords:

CANREB, Beam dynamics, Nier spectrometer, Injection beamline, EBIS beamline, CSB

beamline, RIB transport, LEBT, Mass separator

Contents

1 Introduction 41.1 Purpose and scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41.2 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41.3 Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2 Requirements 72.1 Injection beamline [1] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72.2 Nier-spectrometer [2] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72.3 Constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

3 Beam optics 73.1 Injection beamline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83.2 Nier-Spectrometer (NIS) . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.2.1 Bending magnet . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223.3 Matching section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

4 Tolerances 29

5 Summary 29

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Document-116897

TRI-DN-15-06 Low Energy Beam Transport Line for the CANREB Charge State Breeder Release: 03

Dated: 2016/09/09

Abstract

The low energy beam transport line for the CANREB charge state breeder con-sists of two beamlines: (i) An injection beamline from a RFQ buncher to a chargestate breeder for transportation of singly charged ion beams, and (ii) An extrac-tion beamline, namely a Nier-spectrometer, for mass-over-charge selection. Inthis design note the beam optics design, beamline layout, element specificationsand diagnostic requirements are documented.

1 Introduction

An electron beam ion source (EBIS) is used as a charge state breeder to enhance thecharge state of injected ion into a charge state at high level. The EBIS requires basicallytwo low energy beam transport (LEBT) beamlines for ion beam injection and extraction.A schematic layout of the injection and the Nier-spectrometer (NIS) beamlines is shownin Fig. 1. The first part of the LEBT beamline is called the injection beamline, whichwill be used to transport a singly charged pulsed ion beam from an RFQ buncher intothe EBIS. The second part of the beamline is called as the Nier-spectrometer (NIS). TheNIS beamline will be used to transport the extracted beam from the EBIS as well as toseparate the required highly charged ions from the the background of residual gas ions.A NIS consist of an electrostatic and a magnetic bender, which allows an achromaticmode of operation resulting in a high mass resolving power. The common beamlinebetween the injection and the NIS beamline is called as the EBIS matching section.Function of the matching section is to match the incoming beams into the acceptanceof the EBIS as well as to match the extracted beams from the EBIS into the acceptanceof the NIS. For this purpose the optical elements in the matching section will be pulsed.

1.1 Purpose and scope

Purpose of this design note is to provide some basic information about the functionalityof both beamlines. Scope of this document is to present the conceptual design.

1.2 Definitions

� Coordinate system: Horizontal axis: x, vertical axis: y and beam axis: z. Theinitial beam parameters and the origin of the beamline are assumed at the locationof AGTE:PM41 for the NIS (see Fig. 6). Whereas for the injection beamline theinitial beam parameters and the origin of the beamline are assumed at the locationof RFQ-exit (see Fig. 2).

� Energy slit (AGTC:SLIT7A): A set of slits is used in the NIS beamline (down-stream to the 45◦ electrostatic bender) to limit the energy acceptance (see Fig. 1).

� Mass slit (AGTC:SLIT7B): A set of slits is used in the NIS beamline (down-stream to the magnetic bender) to select the required m/q (see Fig. 1).

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1.3 Abbreviations

� CANREB: CANadian Rare isotope facility with Electron Beam ion source.

� EBIS: Electron Beam Ion Source.

� LEBT: Low Energy Beam Transport.

� NIS: NIer-Spectrometer.

� AGTE: ARIEL Ground level Transport East.

� AGTC: ARIEL Ground level Transport Central.

� EQ: Electrostatic Quadrupole.

� MB: Magnetic Bender.

� EB-EFB: Electrostatic Bender’s Effective Field Boundary.

� MB-EFB: Magnetic Bender’s Effective Field Boundary.

� defx: Electrostatic deflector in the horizontal plane.

� RFQ: Radio Frequency Quadrupole.

� PDT: Pulsed Drift Tube.

� FC: Faraday Cup.

� PM: Profile Monitor.

� COL: COLlimator.

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-2200 -2000 -1800 -1600 -1400 -1200 -1000distance [cm]

7300

7400

7500

7600

7700

7800

7900

8000

8100

dist

ance

[cm

]

EB-45 °

EB-45 °

MB-90 °

defx-9 °

EB-45 °

EB-36 °

Mass slit

Energy slit

q1+

qn+

qn+q1+

q1+

q1+

qn+

Matching sectionInjection beamlineNier-spectrometerVertical beamline

EBIS

RFQCooler/Buncher

Pulsedrifttube

Figure 1: A schematic view of the injection and the Nier-spectrometer beamline on the ARIELground floor. Specified coordinates are with respect to the TRIUMF cyclotron center.

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2 Requirements

2.1 Injection beamline [1]

An injection beanline is required to transport a singly charged ion beams from theRFQ/Buncher through the PDT to the EBIS. The beamline should be capable of trans-porting ion beams with an emittance of 16 µm and beam energy between 10 keV to60 keV.

2.2 Nier-spectrometer [2]

An EBIS is used to produce highly charged ions of injected heavy-ion beams. Ion beamsextracted from an EBIS consist of various mass-over-charge (m/q). The required m/qrange will be 5 ≤ m/q ≤ 7 and the corresponding beam energy (E) range will be10 qkeV ≤ E ≤ 14 qkeV. However, the dipole magnet should be designed to cover am/q up to 50 for measuring charge state distributions both of the required ion beamand residual gas ions. The beamline should be capable of transporting the extracted ionbeams with transverse emittance ≈ 16 µm and the energy spread less than 100 qeV.

The mass resolving power of the spectrometer for a beam defined as above shouldbe M/∆M > 200, with ∆M including 90 % of the beam intensity of all ions with onemass to charge ratio.

In order to allow the beam injection and extraction ion optical elements in thesection between the EBIS and the first electrostatic bender have to be switchable. Thefrequency of the switching will be up to 100 Hz. The pulse length of a singly chargedions to be injected into the EBIS will be 1 µs and the pulse length of a highly chargedions coming out of the EBIS will be up to 1 ms.

In order to minimize the charge exchange loss the vacuum in the dipole magnet hasto be below 4 × 10−8 torr. All the diagnostic elements have to be designed to handlethe pulsed beams going in or coming out of the EBIS. The intensity range to be coveredwill range from several ions per second to average currents up to 1 µA.

2.3 Constraints

� Both beamlines have to fit into the overall design.

� Wherever possible ion optical and beam line elements shall use the same designs,which are used for similar elements within the CANREB project.

� All devices shall be controlled via the standard TRIUMF control system EPICS.

3 Beam optics

The beam optics simulations were performed by using our in-house code TRANSOPTRand the final design of the NIS has been bench-marked with the code GIOS [3] and

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COSY INFINITY [4] up to third-order. The optics calculations for the injection andNIS beamlines are described in Sec. 3.1 and Sec. 3.2, respectively. The optics calculationsfor various matching sections are described in Sec. 3.3.

3.1 Injection beamline

A schematic layout of the injection beamline is shown in Fig. 1. Recently it has beenproposed that the PDT has to be detached from the RFQ buncher and should beinstalled downstream to the 90◦ bender [5, 6]. In order to accomodate its new locationthe injection beamline needs to be redisgned accordingly. The new beamline optics toaccomodate the RFQ buncher and the PDT is reported in this design note.

The injection beamline consists of three triplets and an achromatic 90◦ bend sectionconsisting of two 45◦ spherical benders. The electrode geometries of the quadrupoleand the spherical benders are similar to the ones used in the ISAC-LEBT beamline [7].The initial beam parameters at the location of injection slits are shown in table. 1. Theoptics modules are designed in such a way that to achieve two different tunes accordingto the use of pulsed drift tube (PDT). Use of PDT may be not be required in casea 14 kV beam is transported through the RFQ buncher. In that case tune-1 can beused on order to transport the beam through long drift about 1 m at the location ofPDT by using the triplets for point-to-parallel-to-point transfer. The calculated beamenvelope for tune-1 is shown in Fig. 2. Use of PDT is required if the transported beamthrough the RFQ buncher is higher than the 14 keV. In this case the triplets are used asa doublet by turning of the third quadrupole in the first two triplets in order to matchinto the required beam parameter at the entrance of PDT as shown in table 2. Thistune is called as tune-2 and the calculated envelope for the tune-2 is shown in Fig. 3.The extracted beam from the pulsed drift tube is shown in table 3. The downstreamoptics to the PDT consists of an Einzel lens and the focus is achieved at the location ofAGTE:PM41 (see Fig. 4).

Horizontal size of the beam [2 rms] (x) 5.6 mm

Horizontal size of the beam divergence [2 rms] (x′) 6.7 mrad

Vertical size of the beam [2 rms] (y) 5.6 mm

Vertical size of the beam divergence [2 rms] (y′) 6.7 mrad

Correlation parameter in horizontal plane (r12) -0.84815

Correlation parameter in vertical plane (r34) -0.84815

Emittance [4 rms] (ε) 20.0 µm

Table 1: Initial beam parameters for the injection beamline at the location of RFQ exit [5] (seeFig. 1).

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Correlation parameter in horizontal plane (r12) 0.75962

Correlation parameter in vertical plane (r34) 0.75962


Table 2: Required beam parameters at the location of PDT entrance [6] (see Fig. 1).








Table 3: Required beam parameters at the location of PDT exit [6] (see Fig. 1).

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-2

-1.5-1

-0.5 0

0.5 1

1.5 2

0 1

2 3

4 5

dist

ance

(m

)

RFQ exitXY-steerer25

FC-PM25

EQ26EB-ent.EB26EB-exit

EQ27EQ28PM28EQ29EQ30

EB-ent.EB30EB-exitEQ31

FC31

XY-steerer31EQ32EQ33EQ34


FC-PM37

XY-steerer37

EQ38EQ39EQ40

PM40PDT-ent.

x-en

velo

pe (

cm)

y-en

velo

pe (

cm)

Ene

rgy

disp

ersi

on (

m)

foca

l pow

er (

arb.

)

Figure 2: Calculated beam envelope (2 rms) and energy dispersion for 14 keV ion beam throughthe injection beamline with ε = 16 µm.

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-2

-1.5-1

-0.5 0

0.5 1

1.5 2

0 1

2 3

4 5

dist

ance

(m

)

RFQ exitXY-steerer25

FC-PM25

EQ26EB-ent.EB26EB-exit

EQ27EQ28PM28EQ29EQ30

EB-ent.EB30EB-exitEQ31

FC31



FC-PM37

XY-steerer37

EQ38EQ39EQ40

PM40PDT-ent.

x-en

velo

pe (

cm)

y-en

velo

pe (

cm)

Ene

rgy

disp

ersi

on (

m)

foca

l pow

er (

arb.

)

Figure 3: Calculated beam envelope (2 rms) and energy dispersion for 60 keV ion beam throughthe injection beamline with ε = 16 µm.

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-2

-1.5-1

-0.5 0

0.5 1

1.5 2

0 0

.2 0

.4 0

.6 0

.8 1

dist

ance

(m

)

PDT-exitxy-steerer40

EL-ent.

EL41

EL-exit

D41

PM41

x-en

velo

pe (

cm)

y-en

velo

pe (

cm)

foca

l pow

er (

arb.

)

Figure 4: Calculated beam envelope (2 rms) for 14 keV ion beam through the injection beam-line with ε = 16 µm.

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Name Tune-1 [kV] Tune-2 [kV] R [cm] L [cm] s [cm] x [cm] y [cm] z [cm] θ [deg.]

RFQ-exit - - - - 0.00 0.00 0.00 0.00XY-steerer25 - - - - 100.00 0.00 0.00 966.09FC-PM25 - - - - 683.14 0.00 0.00 1549.22EQ26 0.982 0.982 25.40 50.80 1035.80 0.00 0.00 1901.89EB-ent. - - - - 1147.04 0.00 0.00 2013.13EB26 - - - - 1246.79 -19.33 0.00 2110.33 45◦

EB-exit - - - - 1346.53 -74.39 0.00 2192.73EQ27 -3.633 -3.633 25.40 25.40 1538.70 -210.28 0.00 2328.62EQ28 4.298 4.298 25.40 38.10 1608.55 -259.67 0.00 2378.01PM28 - - - - 1684.36 -313.27 0.00 2431.61EQ29 4.298 4.298 25.40 38.10 1760.17 -366.88 0.00 2485.21EQ30 -3.633 -3.633 25.40 25.40 1830.02 -416.27 0.00 2534.61ent. - - - - 2022.18 -552.15 0.00 2670.49EB-EB30 - - - - 2121.93 -634.56 0.00 2725.55 45◦

exit - - - - 2221.67 -731.76 0.00 2744.88EQ31 0.982 0.982 25.40 50.80 2332.92 -843.00 0.00 2744.88FC31 - - - - 2685.58 -1195.66 0.00 2744.88XY-steerer31 - - - - 2851.55 -1361.63 0.00 2744.88EQ32 3.062 3.165 25.40 50.80 2976.95 -1487.03 0.00 2744.88EQ33 -5.683 -3.165 25.40 50.80 3087.75 -1597.83 0.00 2744.88EQ34 3.062 0.000 25.40 50.80 3198.55 -1708.63 0.00 2744.88XY-steerer34 - - - - 3655.89 -2165.97 0.00 2744.88EQ35 3.062 3.296 25.40 50.80 3781.29 -2291.37 0.00 2744.88EQ36 -5.683 -3.296 25.40 50.80 3892.09 -2402.17 0.00 2744.88EQ37 3.062 0.000 25.40 50.80 4002.89 -2512.97 0.00 2744.88FC-PM37 - - - - 4294.26 -2804.34 0.00 2744.88XY-steerer37 - - - - 4491.96 -3002.03 0.00 2744.88EQ38 2.724 4.641 25.40 50.80 4817.36 -3327.43 0.00 2744.88EQ39 -4.910 -7.905 25.40 50.80 4928.16 -3438.23 0.00 2744.88EQ40 -2.724 4.641 25.40 50.80 5038.96 -3549.03 0.00 2744.88PM40 - - - - 5202.05 -3712.12 0.00 2744.88PDT-ent. - - - - 5265.93 -3776.00 0.00 2744.88

Table 4: The coordinates (x, y, z) coressponds to the local position of the mid-point of theeach optical element and diagnostic device in the injection beamline (AGTE). The 2nd and 3rdcolumn specifies the quadrupole strength in kV for 14 kV and 60 kV ion beams, respectively.The 4th and 5th column specifies the radius (R) and length (L) of the quadrupole in millimeter.The 6th column (s) is the reference trajectory length in millimeter. The 10th column (θ)specifies the bending angle in degree.

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Name Potential [kV] R [cm] L [cm] s [cm] x [cm] y [cm] z [cm] θ [deg.]

PDT-exit - - - 0.00 -4686.00 0.00 2744.88 -XY-steerer40 - - - 33.90 -4719.89 0.00 2744.88 -EL-entr - - - 109.54 -4795.54 0.00 2744.88 -EL41 8.7 25.40 50.80 243.34 -4929.27 0.00 2744.88 -EL-exit - - - 377.82 -5063.67 0.00 2744.88 -defx-D41 - - - 875.50 -5561.36 0.00 2744.88 0◦

PM41 - - - 918.69 -5604.55 0.00 2744.88 -

Table 5: The coordinates (x, y, z) coressponds to the local position of the mid-point of theeach optical element and diagnostic device in the injection beamline (AGTE). The 2nd columnspecifies the Einzel lens strength in kV for 14 kV ion beam. The 3rd and 4th column specifiesthe radius (R) and length (L) of the Einzel lens in millimeter. The 5th column (s) is thereference trajectory length in millimeter. The 9th column (θ) specifies the bending angle indegree.

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3.2 Nier-Spectrometer (NIS)

A NIS consists of an electrostatic and a magnetic dipole element. In our case it containsadditional focusing elements in between the dipoles. The electrostatic bend compensatesthe energy dispersion of the magnetic bend. This allows an achromatic mode of operationresulting in a high mass resolving power even for beams with a high energy spread as inthe case of extracted beams from an EBIS. In the case of an extraction voltage of 20 kV,the highest expected energy spread is up to 100 V (i.e., δE = 0.25 %). The requiredmass resolving power is about 200 (i.e., δm = 0.5 %).

A schematic layout of the NIS beamline is shown in Fig. 1. The geometry of theelectrostatic optical elements is similar to the optical elements used in the ISAC-LEBTbeamline. The requirement of the bending magnet is briefly described in Sec. 3.2.1 anda detail design requirement can be found in the Ref. [8].

Maximal mass deviation (δm) 0.5 %

Energy deviation (δE [2 rms]) at 20 qkeV 0.25 %







Emittance [4 rms] (ε) (16 µm)

Table 6: Initial beam parameters for the NIS at the location of PM41 (see Fig. 6).

The system has been calculated to first-order with the code TRANSOPTR and alsoit has been bench-marked with the code GIOS and COSY INFINITY up to third-order.The initial beam parameters are assumed at the location of the AGTE:PM41 as shownin table 6. The calculated beam envelope and energy dispersion for the NIS by usingthe code TRANSOPTR is shown Fig. 6. Fig. 5 shows the calculated ion trajectoriesthrough the beamline for three different mass with a mass difference of δm = ± 0.5 %.An adjustable horizontal slit (energy slit) can be used to define the energy acceptanceto δE ≤ 0.25 %. The energy slit will be installed at the first focal point, which is about614.2 mm upstream to the entrance edge of the bending magnet (see Fig. 1). In orderto select a required m/q another slit will be installed at the location of the second focalpoint, which is about 614.2 mm downstream to the exit edge of the bending magnet (seeFig. 1).

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Figure 5: Nier-Spectrometer layout with the calculated ion trajectories (for δE = ± 0.25 %and δm = ± 0.5 %) by using the code GIOS.

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-2

-1.5-1

-0.5 0

0.5 1

1.5 2

0 1

2 3

4 5

dist

ance

(m

)

FC-PM41 defx-D41

EB-ent.EB1EB-exit

EQ1PM1EQ2

EB-ent.EB2EB-exit

EQ3XY-steerer3FC-PM3

EQ4EQ5

PM5XY-steerer5EQ6EQ7

SLIT7AY-steerer7A

MB-ent.

MB0

MB-exit

SLIT7BFC-PM7B

x-en

velo

pe (

cm)

y-en

velo

pe (

cm)

Ene

rgy

disp

ersi

on (

m)

Mas

s di

sper

sion

(m

)fo

cal p

ower

(ar

b.)

Figure 6: Calculated beam envelope (2 rms) and energy dispersion for 266 keV 133Cs19+ ionbeam through the NIS with ε = 16 µm.

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Calculated spatial distribution at the location of the mass slit by using the codeGIOS is shown in Fig. 7. For the same beam the horizontal and the vertical phase-spacedistributions are shown in Fig. 8 and 9, respectively. At the location of the mass slitthe first-order optics calculation shows a linear magnification of (x|x) = 0.75, a energydispersion of (x|δE) ≈ 0 and a mass dispersion of (x|δm) = 0.614 m.

In the linear approximation:

1. Energy resolving power at the location of energy slit,

RK =(x|δE)

2(x|x)W≈ 192 (1)

where (x|δE) = 0.614 m is the energy dispersion,(x|x) = 0.80 is the magnification, andW = 2× 10−3 m is the half width of the source slit.

2. Mass resolving power at the location of mass slit,

Rm =(x|δm)

2(x|x)W≈ 205 (2)

where (x|δm) = 0.614 m is the mass dispersion,(x|x) = 0.75 is the magnification, andW = 2× 10−3 m is the half width of the source slit.

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-8 -4 0 4 8mm

-24

-16

-8

0

8

16

24

mra

d

x-Px

Figure 7: Calculated phase-space profiles in the horizontal plane at the location of massselection slit AGTC:SLIT7B (see Fig. 1 or 6) for a 14 kV beam with δE = ± 0.25 % andδm = ± 0.5 % by using the code COSY INFINITY.

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-8 -4 0 4 8mm

-24

-16

-8

0

8

16

24

mra

d

x-Px

ǫ = 32 µmǫ = 16 µmǫ = 8 µm

Figure 8: Calculated phase-space profiles for various beam emittances in the horizontal planeat the location of mass selection slit AGTC:SLIT7B (see Fig. 1 or 6) for a 14 kV beam withδE = ± 0.25 % and δm = ± 0.5 % by using the code COSY INFINITY.

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-8 -4 0 4 8mm

-24

-16

-8

0

8

16

24

mra

d

y-Py

ǫ = 32 µmǫ = 16 µmǫ = 8 µm

Figure 9: Calculated phase-space profiles for various beam emittances in the vertical planeat the location of mass selection slit AGTC:SLIT7B (see Fig. 1 or 6) for a 14 kV beam withδE = ± 0.25 % and δm = ± 0.5 % by using the code COSY INFINITY.

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0 10 20 30 40 50Emittance [ µm]

0

50

100

150

200

250

300

350

400R

esol

ving

pow

er

Figure 10: Calculated mass resolving power at the location of mass selection slit in the Nier-spectrometer for various beam emittance.

3.2.1 Bending magnet

Magnet type Rotated pole faceBending angle (θ) 90◦

Pole face rotation angle (entrance and exit) 22.5◦

Bending radius (ρ) 360 mmFull air gap (Non-bend plane) 60.0 mmMaximum field strength (Bmax) ≥ 0.5656 TField homogeneity (∆

∫Bdl)/(

∫Bdl) (see Fig. 12) ≤ 4× 10−4

Table 7: Summary of the basic magnet requirements.

From the rigidity and bending angle (θ), the required field integral is:∫ +∞

−∞Bdl = (Bρ)max × θ ' 0.31983 [T m] (3)

The increment dl is taken along the ion trajectory.

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Figure 11: Vertical cross-section at the magnet center. Measurements in mm.

Figure 12: Plan view of magnet pole in the horizontal plane. Measurements in mm and degree.

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Name Pot. [kV] R [mm] L [mm] s [mm] x [mm] y [mm] z [mm] θ [deg.]

FC-PM41 - - - 0.00 0.00 0.00 0.00 -defx-D41 - - - 43.18 0.00 0.00 43.18 9◦

EB-ent. - - - 280.92 37.19 0.00 278.00 -EB1 - - - 360.72 61.75 0.00 353.58 36◦

EB-exit - - - 440.52 108.46 0.00 417.87 -EQ1 0.654 25.40 50.80 679.57 277.50 0.00 586.90 -PM1 - - - 745.86 324.37 0.00 633.78 -EQ2 0.438 25.40 50.80 812.15 371.24 0.00 680.65 -EB-ent. - - - 1066.26 550.92 0.00 860.33 -EB2 - - - 1166.00 633.33 0.00 915.39 45◦

EB-exit - - - 1265.75 730.53 0.00 934.73 -EQ3 1.067 25.40 50.80 1480.42 945.20 0.00 934.73 -XY-steerer3 - - - 1574.24 1039.02 0.00 934.73 -FC-PM3 - - - 1651.16 1115.94 0.00 934.73 -EQ4 1.009 25.40 50.80 2012.11 1476.89 0.00 934.73 -EQ5 0.307 25.40 50.80 2118.85 1583.63 0.00 934.73 -PM5 - - - 2274.94 1739.72 0.00 934.73 -XY-Steerer5 - - - 2362.65 1827.43 0.00 934.73 -EQ6 0.307 25.40 50.80 2431.03 1895.82 0.00 934.73 -EQ7 1.009 25.40 50.80 2537.78 2002.56 0.00 934.73 -SLIT7A - - - 2898.73 2363.51 0.00 934.73 -Y-Steerer7A - - - 2973.73 2438.51 0.00 934.73 -MB-ent. - - - 3512.93 2977.71 0.00 934.73 -MB0 - - - 3795.67 3232.26 0.00 1040.17 90◦

MB-exit - - - 4078.41 3337.70 0.00 1294.73 -SLIT7B - - - 4692.61 3337.70 0.00 1908.93 -FC-PM7B - - - 4742.62 3337.70 0.00 1958.93 -

Table 8: The coordinates (x, y, z) coressponds to the local position of the mid-point of theeach optical element and diagnostic device in the NIS beamline (AGTE and AGTC). The 2ndcolumn (pot.) specifies the quadrupole strength in kV for 14 kV ion beam. The 3rd and4th column specifies the radius (R) and length (L) of the quadrupole in millimeter. The 5thcolumn (s) is the reference trajectory length in millimeter. The 9th column (θ) specifies thebending angle in degree.

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3.3 Matching section

The CANREB CSB beamline consists of various matching sections:EBIS matching, Nierexit matching and RFQ entrance matching (see Fig.1). The beam optics design for theEBIS matching section, i.e. the optics between AGTE:EBIS and AGTE:PM41 is notdocumented in this design note. This work is in progress with the simulation resultsobtained from the EBIS injection/extraction simulations. The EBIS matching sectionwill be designed in such a way that the incoming beams to the EBIS and the outgoingbeams from the EBIS are matched properly to their respective beamline. This will beachieved by pulsing the optical elements in this matching section. In order to kick theextracted beam from the EBIS to the NIS, an electrostatic deflector (AGTE:defx-D41)is used by modifying a single 45◦ bender, splitting it into a 9◦ electrostatic deflector and36◦ spherical bender [7].

The calculated beam envelope for the beamline that connects the NIS and ARIELRIB beamline is shown in Fig. 13. Required beam parameter at the entrance RFQbuncher is shown in table 10. Fig. 14 shows the calculated beam envelope for thebeamline that connects ARIEL RIB beamline and the RFQ buncher.

Name Pot. [kV] R [mm] L [mm] s [mm] x [mm] y [mm] z [mm]

SLIT7B - - - 4692.62 3337.71 0.00 1908.93FC-PM7B - - - 4742.62 3337.71 0.00 1958.93XY-steerer7B - - - 4792.62 3337.71 0.00 2008.93EQ8 -0.374 25.40 50.80 4868.02 3337.71 0.00 2084.33EQ9 0.917 25.40 50.80 4992.93 3337.71 0.00 2209.24EQ10 -0.880 25.40 50.80 5099.46 3337.71 0.00 2315.77EQ11 0.792 25.40 50.80 5231.58 3337.71 0.00 2447.89PM11 - 25.40 50.80 5388.58 3337.71 0.00 2604.89

Table 9: The coordinates (x, y, z) coressponds to the local position of the mid-point of theeach optical element and diagnostic device in the matching section downstream to the NISbeamline (AGTC). The 2nd column (pot.) specifies the quadrupole strength in kV for 14 kVion beam. The 3rd and 4th column specifies the radius (R) and length (L) of the quadrupolein millimeter. The 5th column (s) is the reference trajectory length in millimeter.

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-2

-1.5-1

-0.5 0

0.5 1

1.5 2

4.7

4.8

4.9

5 5

.1 5

.2 5

.3 5

.4

dist

ance

(m

)

SLIT7B

FC-PM7B

XY-steerer7B

EQ8

EQ9

EQ10

EQ11

PM11

x-en

velo

pe (

cm)

y-en

velo

pe (

cm)

foca

l pow

er (

arb.

)

Figure 13: Calculated beam envelope (2 rms) and energy dispersion for 20 keV ion beamthrough the NIS with ε = 16 µm.

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-2

-1.5-1

-0.5 0

0.5 1

1.5 2

0 0

.1 0

.2 0

.3 0

.4 0

.5 0

.6 0

.7 0

.8

dist

ance

(m

)

XY-Steerer21

EQ22

EQ23

FC-PM23

EQ24

EQ25

RFQ ent

x-en

velo

pe (

cm)

y-en

velo

pe (

cm)

foca

l pow

er (

arb.

)

Figure 14: Calculated beam envelope (2 rms) and energy dispersion for 20 keV ion beamthrough the injection beamline with ε = 16 µm.

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Maximum beam energy 60 keV








Table 10: Required beam parameters at the location of RFQ buncher entrance [5] (see Fig. 1).

Name Pot. [kV] R [mm] L [mm] s [mm] x [mm] y [mm] z [mm]

XY-Steerer21 - - - 000.00 0.00 0.00 000.00EQ22 2.645 25.40 50.80 117.00 0.00 0.00 117.00EQ23 -1.154 25.40 50.80 207.99 0.00 0.00 207.99FC-PM23 - - - 330.35 0.00 0.00 330.35EQ24 -3.225 25.40 50.80 452.70 0.00 0.00 452.70EQ25 1.892 25.40 50.80 543.69 0.00 0.00 543.69RFQ-ent. - - - 780.09 0.00 0.00 780.09

Table 11: The coordinates (x, y, z) coressponds to the local position of the mid-point ofthe each optical element and diagnostic device in the matching section upstream to the RFQbuncher (AGTE). The 2nd column (pot.) specifies the quadrupole strength in kV for 14 kVion beam. The 3rd and 4th column specifies the radius (R) and length (L) of the quadrupolein millimeter. The 5th column (s) is the reference trajectory length in millimeter.

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4 Tolerances

The integrated field along the beam path must be no larger than about 90 gauss cm.The local ambient field bumps should be less than 1 gauss. Tolerances for the trans-verse positioning of the nier dipole magnet (AGTC:MB0) should be less than 1 mm.Mechanical and electrical tolerances for the electrostatic elements can be similar to thespecified tolerance for electrostatic elements used in the ARIEL RIB transport [9].

5 Summary

Beam optics design for a Nier-spectrometer has been done to achieve a resolving power of200 for a given emittance of 16 µm at an extraction potential of 14 kV. Injection beam-line optics has been redesigned to accommodate the PDT at the proposed location, i.e.downstream to the 90◦ achromatic section. Beam optics calculations also includes therequired matching sections for the CANREB CSB beamline. Optical elements and itsdesign details are presented.

References

[1] J. Dilling, CANREB RFQ Buncher, Document-92050, Internal report, TRIUMF,July, 2013.

[2] F. Ames, CANREB Nier-spectrometer, Document-91140, Internal report, TRIUMF,July, 2013.

[3] H. Wollnik et al., Nucl. Instr. and Meth. A 258 (1987) 408.

[4] M. Bertz et al.,, COSY INFINITY Version 8.1, see http://cosy.pa.msu.edu.

[5] B. Barquest, CANREB RFQ Beam Cooler, TRI-DN-15-07, Internal report, TRI-UMF, July, 2015.

[6] B. Barquest, Design note for pulsed drift tube relocation, TRI-DN-16-10, Internalreport, TRIUMF, April, 2016.

[7] R. Baartman, ISAC LEBT, TRI-BN-12-10, Internal report, TRIUMF, July, 2012.

[8] S. Saminathan, Dipole magnet requirements for Nier-Spectrometer, TRI-DN-15-09,Internal report, TRIUMF, Jan., 2015.

[9] M. Marchetto, and S. Saminathan, ARIEL Front-End Design Note, Document-41767, Internal report, TRIUMF, June, 2015.

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design note tri dn low energy beam transport line for the...

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