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3.2 Experimental Setup and Simulation Geometry

3.2.2 Analysis Process with ROOT

SAVE #1

∗−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−

This save point will store all the data of all particles inside the simulation at the point. The data is stored within a ROOT Tree as an array. Following properties are saved as floats:

• y andxcoordinates

• corresponding momentum as angles to beam axis (aandb)

• the beam energy

• simulation time

• mass, charge and number of electrons of the particle

• scattering anglesφandθ

• additional beam optics properties

3.2.2 Analysis Process with ROOT

This section gives a brief overview of the used analysis script, which processed the data from MOCADI.

As an analysis software ROOT was used since MOCADI ouputs compatible files. ROOT is handled with a C++ script which is compiled with in ROOT.

Input

The input data are 2-3 input files from MOCADI according to section3.2.1and following. These files have all variables stored in an array with the size of the number of save points up to an maximum of 15. The storedTTrees are than being stored inside ofTChains and can then be processed.

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24 CHAPTER 3. EXPERIMENTAL FACILITY AND ION OPTICS SIMULATION Histogram Filling and Elastic Scattering

For each detector position, event hit-distributions in x−y coordinates in the detector planes, are generated. Because every event is tagged by its corresponding (θ, φ)cm, that was sampled in a save point -1- in MOCADI at the target, a Rutherford weighting can be apply, event by event, to each event according to its original θcm. In this way, the final hit distributions in the detector planes correctly represent Rutherford elastic scattering of the 33,34mCl beam at the gas target position. However, the singularity atθ= 0must be avoided in the weighting, and we therefore apply the weighting up to a lower cut-off angle of5. This is only needed in case of elastic scattering.

Listing 3.6: Rutherford weighting inside the ROOT analysing script h i s t x y p p [ h i s c o u n t ]−> F i l l ( pp_x [ h i s c o u n t ] ,

pp_y [ h i s c o u n t ] ,

pow ( 1 / s i n ( pp_theta [ 1 ]∗TMath : : Pi ( ) / 1 8 0 . / 2 . ) , 4 ) ) ; Events within a narrow range ofθandθ+ dθandφandφ+ dφland in a "narrow" range ofxandy.

In Figure3.4the relation can be seen for different angles. The CMS angles φandθare store in save point -1-.

x [cm]

6 4 2 0 2 4 6

y [cm]

5

4

3

2

1 0 1 2 3 4 5

1st Detector Position 2 max [5]

Figure 3.4: Hit patterns inx andy for different θ andφ in CMS after the reaction has occurred at the second possible detector position inside the dipole section -5-:

Red: θ = 20, φ = 130; Blue: θ = 20, φ = 180; Green: θ = 20, φ = 310; Violet: θ = 20, φ= 360; Brown: θ= 30,φ= 220; Orange: θ= 30,φ= 50

But the weighting according to the Rutherford cross section has the disadvantage of a indefinite pole at the origin. Therefore a cut is applied for θ < θcut = 5. The histogram is still not showing the right count rates since it is not normalized. This is done by computing the Rutherford cross section of each resonance energy from the cutoff angleθcuttoπ:

σR= 2π·

Z1Z2e2 4Er

2

· Z π

θcut

sin(θ)

sin4 θ2dθ (3.2)

This then gives the effective cross section inside the angular disk around the center of the beam. The calculated elastic cross section for the different resonance energies of33Cl(p, γ)34Arand34mCl(p, γ)35Ar are shown in Table3.2.

Detector Plane

Since MOACDI has no dedicated detectors or detector planes, they were implemented via graphical cuts (TCutG). The CRYRING limits the detector size and also how near they can be placed to the beam axis.

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3.2. EXPERIMENTAL SETUP AND SIMULATION GEOMETRY 25 Table 3.2: Calculated Rutherford elastic cross section for each resonance energy of33Cl(p, γ)34Arand

34Cl(p, γ)35Arwithin 5 to180

33Cl(p, γ)34Ar

Resonance energyEr[keV] Rutherford Cross SectionσR [kb]

201 58.4649670253

303 25.7277950178

561 7.5051970882

646 5.6600828456

878 3.0640707717

956 2.5844732375

34Cl(p, γ)35Ar

Resonance energyEr[keV] Rutherford Cross SectionσR [kb]

110 195.55

215 51.19

588 6.84

784 3.85

916 2.82

To get a better understanding of the event rates and to pin down the detector size two different sized detector planes were used. A bigger one with the size of4 cm by6 cm was used to get a total detector area of24 cm2. The positioning to the beam axis is mainly determined by the archived beam emittance, but values around1.5 cm should be achievable. For a conservative approach this detector plane is placed2 cmaway from the beam axis.

A smaller one with a size of2 cmby4 cmwith a total area of8 cm2was also used. This one is placed further away from the beam axis (4 cm) to catch less elastic background. These detector planes are the same on every possible detector position (see Figure3.3). The positioning of both detector planes in comparison to a circulating beam in the ring can be seen in Figure3.5.

Thexaxis points towards the center of the ring and theyandzaxis are set according to the coordinate system shown in Figure2.3(mirrored setup as shown since the beam is circulating anticlockwise). This coordinate system is the same for all figures showing the beam propagation.

x [cm]

-6 -4 -2 0 2 4 6

y[cm]

-5 -4 -3 -2 -1 0 1 2 3 4 5

Events

1 10 102 103 104 105 106 107 108 Initial Beam [0]

1

Figure 3.5: Positioning of the two detector planes inside the beam pipe in comparison to a circulating beam at the origin

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26 CHAPTER 3. EXPERIMENTAL FACILITY AND ION OPTICS SIMULATION

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Chapter 4

Results

4.1 Effective elastic cross sections and Fusion Product Cover-age for different Detector Positions and Sizes

This section presents the elastic scattering yields at each detector position for the33Cl(p, γ)34Arand

34mCl(p, γ)35Arreactions with the focus on thexandyhit distribution and fraction of particles hitting the detector plane. All results are shown with emittance disabled. For the results with emittance enabled see sectionB.2 in the appendix.

4.1.1

33

Cl(p, γ)

34

Ar

In Figure4.1the fusion products and elastic scattering hit distribution for the33Cl(p, γ)34Arreaction on each detector position are shown for the lowest resonance at201 keV. Black rectangles represent the small and big detector plane. The vertical cutoffs seen in Figure4.1a, 4.1b and4.1c are due to the8 cmhigh beam pipe inside the dipole magnet. In addition, collimators located between detector positions -5- and -7- and positions -9- and -10 cause the other cut-offs seen in the data plots.

The fusion products and a non-negligible fraction of elastically scattered beam are not spatially sep-arated and the scattered particles contribute to the background in a significant manner. This can also be seen from Table4.1, where the fraction of elastic scattered beam and effective cross sections inside the detector plane and the coverage of fusion events per detector position and size are shown. The effective cross section is defined as

σeff =Ndet/Ntot·σR (4.1)

whereNdet/Ntotis the fraction of beam hitting the detector andσRthe cross section of elastic scattered beam inside the angular range5to180for the CMS scattering angleθcalculated with equation3.2.

Fusion and elastic distribution results are not represented according to their relative cross sections to each other.

Low elastic yields can be achieved at the detector positions -7-, -8- and -9-. Position -9- has the lowest of them. The larger detector would give a better coverage of the fusion products, but suffers from more scattering events. At position -9- it has the highest coverage of fusion products. The smaller detector has the best34Ar coverage at position -10-, but has also the highest effective cross section at this position.

For beam energies corresponding to resonances,303 keV,561 keV, 646 keVand878 keV, the effective Rutherford cross section and the fusion product coverage of the different detector planes are shown in Tables 4.2, 4.3, 4.4 and 4.5. For higher resonance energies the effective elastic cross section gets smaller due to theEr−2dependence as described in equation 3.2. For the highest resonance energy of

27

28 CHAPTER 4. RESULTS Er= 956 keV the hit patterns can be seen in Figure4.2 and the detector coverage of34Ar as well as the effective cross sections are seen in Table4.6.

The fusion products as well as the elastically scattered ions are even more focused than at lower energies. This results in a lower effective elastic cross section for the detectors and also for the detector coverage of the fusion products as seen in Table4.6.

The coverage for fusion events on the larger detector plane is very good from position -7- on, with the lowest effective cross section of scattered beam at position -9-. Because of its size the smaller detector plane can only cover the fusion products for positions -7- to -9-. The lowest scattering cross section and the best 34Ar coverage can be reported at position -9-.

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4.1. EFFECTIVE ELASTIC CROSS SECTIONS AND FUSION PRODUCT COVERAGE FOR

DIFFERENT DETECTOR POSITIONS AND SIZES 29

Table 4.1: Fraction of scattered beam inside the detector plane,Ndet/Ntot, and effective Rutherford cross section of elastic scattered particles, σReff, and detector coverage of fusion products, A34Ar, inside detector planes at Er = 201 keV for different detector positions for 33Cl(p, γ)34Ar reaction.

Both reaction channels are simulated with 1000000 particles.

Detector Small Detector Big Detector

position Ndet/Ntot [10−2] σReff [b] A34Ar [%] Ndet/Ntot [10−2] σReff [kb] A34Ar [%]

-3- 0.24 138.78 0 2.81 1.65 41.48

-4- 0.26 153.72 0.23 3.05 1.79 48.66

-5- 0.27 158.75 1.5 3.13 1.83 50.88

-7- 0.19 108.75 22.99 3.55 2.08 68.36

-8- 0.12 68.05 26.68 2.99 1.75 78.88

-9- 0.06 37.4 28.08 2.49 1.46 79.41

-10- 0.29 170.62 76.02 3.91 2.28 76.02

x [cm] 1st Detector Position 1 [3]

1 1st Detector Position 2 min [4]

1 1st Detector Position 2 max [5]

1 2nd Detector minimum Position [7]

1 2nd Detector middle Position [8]

1 2nd Detector maximum Position [9]

1

Figure 4.1: xyhit distribution for33Cl(p, γ)34Arat resonance energyEr= 201 keV: elastic scattering (mostly green with a big spike at the middle, forθ≥5) and fusion products (pattern superimposed on top of elastic scattered beam, on the right hand side) with two detector planes (big and small rectangle) on the different possible detector positions: dipole: a,b, c; after quadrupole: d,e,f; after first hexapole: g. The cutoffs are due to beam pipe restrictions.

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30 CHAPTER 4. RESULTS

Table 4.2: Fraction of scattered beam inside the detector plane, Ndet/Ntot, and effective Rutherford cross section of elastic scattered particles, σReff, and detector coverage of fusion products, A34Ar, inside detector planes at Er = 303 keV for different detector positions for 33Cl(p, γ)34Ar reaction.

Both reaction channels are simulated with 1000000 particles.

Detector Small Detector Big Detector

position Ndet/Ntot [10−2] σReff [b] A34Ar [%] Ndet/Ntot [10−2] σReff [kb] A34Ar [%]

-3- 0.24 61.07 0 2.81 0.72 39.75

-4- 0.26 67.65 0 3.05 0.79 48.39

-5- 0.27 69.86 0 3.13 0.81 51.06

-7- 0.19 47.85 27.77 3.55 0.91 82.16

-8- 0.12 29.94 38.44 2.99 0.77 85.41

-9- 0.06 16.45 47.73 2.49 0.64 85.41

-10- 0.29 75.05 74.1 3.91 1 74.1

Table 4.3: Fraction of scattered beam inside the detector plane, Ndet/Ntot, and effective Rutherford cross section of elastic scattered particles, σReff, and detector coverage of fusion products, A34Ar, inside detector planes at Er = 561 keV for different detector positions for 33Cl(p, γ)34Ar reaction.

Both reaction channels are simulated with 1000000 particles.

Detector Small Detector Big Detector

position Ndet/Ntot [10−2] σReff [b] A34Ar [%] Ndet/Ntot [10−2] σReff [kb] A34Ar [%]

-3- 0.24 17.81 0 2.81 0.21 36.74

-4- 0.26 19.73 0 3.05 0.23 51.36

-5- 0.27 20.38 0 3.13 0.23 51.18

-7- 0.19 13.96 35.87 3.55 0.27 95.73

-8- 0.12 8.73 49.66 2.99 0.22 95.73

-9- 0.06 4.8 65.07 2.49 0.19 95.73

-10- 0.29 21.89 0.13 3.91 0.29 0.13

Table 4.4: Fraction of scattered beam inside the detector plane, Ndet/Ntot, and effective Rutherford cross section of elastic scattered particles, σReff, and detector coverage of fusion products, A34Ar, inside detector planes at Er = 646 keV for different detector positions for 33Cl(p, γ)34Ar reaction.

Both reaction channels are simulated with 1000000 particles.

Detector Small Detector Big Detector

position Ndet/Ntot [10−2] σReff [b] A34Ar [%] Ndet/Ntot [10−2] σReff [kb] A34Ar [%]

-3- 0.24 13.43 0 2.81 0.16 35.99

-4- 0.26 14.88 0 3.05 0.17 47.81

-5- 0.27 15.37 0 3.13 0.18 51.43

-7- 0.19 10.52 37.31 3.55 0.2 97.72

-8- 0.12 6.59 51.88 2.99 0.17 97.72

-9- 0.06 3.62 68.15 2.49 0.14 97.72

-10- 0.29 16.51 0 3.91 0.22 0

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4.1. EFFECTIVE ELASTIC CROSS SECTIONS AND FUSION PRODUCT COVERAGE FOR

DIFFERENT DETECTOR POSITIONS AND SIZES 31

Table 4.5: Fraction of scattered beam inside the detector plane,Ndet/Ntot, and effective Rutherford cross section of elastic scattered particles, σReff, and detector coverage of fusion products, A34Ar, inside detector planes at Er = 878 keV for different detector positions for 33Cl(p, γ)34Ar reaction.

Both reaction channels are simulated with 1000000 particles.

Detector Small Detector Big Detector

position Ndet/Ntot [10−2] σReff [b] A34Ar [%] Ndet/Ntot [10−2] σReff [kb] A34Ar [%]

-3- 0.24 7.27 0 2.81 0.09 34.37

-4- 0.26 8.06 0 3.05 0.09 47.56

-5- 0.27 8.32 0 3.13 0.1 51.61

-7- 0.19 5.7 38.2 3.55 0.11 99.82

-8- 0.12 3.57 54.49 2.99 0.09 99.82

-9- 0.06 1.96 72.67 2.49 0.08 99.82

-10- 0.29 8.94 0 3.91 0.12 0

Table 4.6: Fraction of scattered beam inside the detector plane,Ndet/Ntot, and effective Rutherford cross section of elastic scattered particles, σReff, and detector coverage of fusion products, A34Ar, inside detector planes at Er = 956 keV for different detector positions for 33Cl(p, γ)34Ar reaction.

Both reaction channels are simulated with 1000000 particles.

Detector Small Detector Big Detector

position Ndet/Ntot [10−2] σReff [b] A34Ar [%] Ndet/Ntot [10−2] σReff [kb] A34Ar [%]

-3- 0.24 6.13 0 2.81 0.07 33.91

-4- 0.26 6.8 0 3.05 0.08 47.49

-5- 0.27 7.02 0 3.13 0.08 51.66

-7- 0.19 4.81 38.01 3.55 0.09 99.96

-8- 0.12 3.01 54.78 2.99 0.08 99.96

-9- 0.06 1.65 73.49 2.49 0.06 99.96

-10- 0.29 7.54 0 3.91 0.1 0

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32 CHAPTER 4. RESULTS 1st Detector Position 1 [3]

1 1st Detector Position 2 min [4]

1 1st Detector Position 2 max [5]

1 2nd Detector minimum Position [7]

1 2nd Detector middle Position [8]

1 2nd Detector maximum Position [9]

1

Figure 4.2: xyhit distribution for 33Cl(p, γ)34Arat resonance energyEr= 956 keV: elastic scattering (mostly green with a big spike at the middle, forθ≥5) and fusion products (pattern superimposed on top of elastic scattered beam, on the right hand side) with two detector planes (big and small rectangle) on the different possible detector positions: dipole: a, b,c; after quadrupole: d,e,f; after first hexapole: g. The cutoffs are due to beam pipe restrictions.

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4.1. EFFECTIVE ELASTIC CROSS SECTIONS AND FUSION PRODUCT COVERAGE FOR

DIFFERENT DETECTOR POSITIONS AND SIZES 33

4.1.2

34m

Cl(p, γ)

35

Ar

In Figure4.3the hit distribution of fusion products and elastic scattered particles for the34mCl(p, γ)35Ar reaction on each detector position are shown for the lowest resonance at110 keV. The cutoffs corres-pond to different collimators between the detector positions as described in the previous section.

At this low energy, the kinematics of the(p, γ)reaction causes non-negligible transverse momentum for the 35Ar fusion products, resulting in a broad hit pattern on the detector plane. Therefore the small detector can only see a very small amount of them. Only after the first quadrupole does one get a good coverage inside the detector. Effective elastic cross sections for 34mCl beam and fusion product coverage per detector position and size can be seen in Table4.7.

At position -9- after the quadrupole the elastic cross section is low and the best coverage of the fusion products for the small detector can be reported. The smaller detector receives less elastic events than does the bigger one.

For resonances with respective energy 215 keV, 588 keV and 784 keV the fusion products are more focused and their subsequent hit distribution in the detector planes are seen to be smaller than in the case of the110 keVresonance. The effective scattering cross section gets smaller according to the E−2r dependence as described in equation3.2.

In Tables4.8,4.9and4.10the 34mCl effective elastic cross sections and the 35Ar coverage inside the small and big detector for higher resonances at the different positions are shown.

The detector position furthest downstream of the quadrupole, at detector position -9-, has the lowest effective cross section and gets a good coverage of the fusion products trough out the resonance energies. As the energies get higher the small detector has better coverage then at the lower resonance energies.

For the last resonance at916 keVthe hit distributions on the detector positions are shown in Figure 4.4and the effective elastic cross section as well as the35Ar coverage are shown in Table4.11.

The lowest effective elastic cross section is at the position -9- after the quadrupole. The coverage of the fusion products gets even better than for lower energies, up to a value of64 % for the small detector. This can also be seen very easily in Figure4.4fas the detector plane can cover a large area of the fusion products.

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34 CHAPTER 4. RESULTS 1st Detector Position 1 [3]

1 1st Detector Position 2 min [4]

1 1st Detector Position 2 max [5]

1 2nd Detector minimum Position [7]

1 2nd Detector middle Position [8]

1 2nd Detector maximum Position [9]

1

Figure 4.3: xyhit distribution for34mCl(p, γ)35Arat resonance energyEr= 110 keV: elastic scattering (mostly green with a big spike at the middle, forθ≥5) and fusion products (pattern superimposed on top of elastic scattered beam, on the right hand side) with two detector planes (big and small rectangle) on the different possible detector positions: dipole: a, b,c; after quadrupole: d,e,f; after first hexapole: g. The cutoffs are due to beam pipe restrictions.

Table 4.7: Fraction of scattered beam inside the detector plane, Ndet/Ntot, and effective Rutherford cross section of elastic scattered particles,σReff, and detector coverage of fusion products,A35Ar, inside detector planes at Er = 110 keVfor different detector positions for 34mCl(p, γ)35Ar reaction. Both reaction channels are simulated with 1000000 particles.

Detector Small Detector Big Detector

position Ndet/Ntot [10−2] σReff [b] A35Ar [%] Ndet/Ntot [10−2] σReff [kb] A35Ar [%]

-3- 0.22 439.5 13.39 2.67 5.22 44.91

-4- 0.25 484.04 17.86 2.88 5.64 49.24

-5- 0.26 499.52 19.02 2.96 5.78 50.59

-7- 0.17 341.64 6.08 3.32 6.5 33.09

-8- 0.11 215.47 7.28 2.82 5.52 32.71

-9- 0.06 115.62 8.06 2.35 4.6 34.15

-10- 0.28 541.88 35.77 3.7 7.24 64.73

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4.1. EFFECTIVE ELASTIC CROSS SECTIONS AND FUSION PRODUCT COVERAGE FOR

DIFFERENT DETECTOR POSITIONS AND SIZES 35

Table 4.8: Fraction of scattered beam inside the detector plane,Ndet/Ntot, and effective Rutherford cross section of elastic scattered particles,σReff, and detector coverage of fusion products,A35Ar, inside detector planes at Er = 215 keV for different detector positions for 34mCl(p, γ)35Ar reaction. Both reaction channels are simulated with 1000000 particles.

Detector Small Detector Big Detector

position Ndet/Ntot [10−2] σReff [b] A35Ar [%] Ndet/Ntot [10−2] σReff [kb] A35Ar [%]

-3- 0.22 115.05 0.6 2.67 1.37 42.98

-4- 0.25 126.7 7.24 2.88 1.48 48.92

-5- 0.26 130.76 9.54 2.96 1.51 50.77

-7- 0.17 89.43 13.65 3.32 1.7 56.62

-8- 0.11 56.4 15.24 2.82 1.44 66.11

-9- 0.06 30.27 16.89 2.35 1.2 73.53

-10- 0.28 141.84 72.71 3.7 1.9 72.73

Table 4.9: Fraction of scattered beam inside the detector plane,Ndet/Ntot, and effective Rutherford cross section of elastic scattered particles,σReff, and detector coverage of fusion products,A35Ar, inside detector planes at Er = 588 keV for different detector positions for 34mCl(p, γ)35Ar reaction. Both reaction channels are simulated with 1000000 particles.

Detector Small Detector Big Detector

position Ndet/Ntot [10−2] σReff [b] A35Ar [%] Ndet/Ntot [10−2] σReff [kb] A35Ar [%]

-3- 0.22 15.38 0 2.67 0.18 39.02

-4- 0.25 16.94 0 2.88 0.2 48.31

-5- 0.26 17.48 0 2.96 0.2 51.18

-7- 0.17 11.96 29.85 3.32 0.23 87.15

-8- 0.11 7.54 41.34 2.82 0.19 87.98

-9- 0.06 4.05 54 2.35 0.16 87.98

-10- 0.28 18.96 63.16 3.7 0.25 63.16

Table 4.10: Fraction of scattered beam inside the detector plane,Ndet/Ntot, and effective Rutherford cross section of elastic scattered particles,σReff, and detector coverage of fusion products,A35Ar, inside detector planes at Er = 784 keV for different detector positions for 34mCl(p, γ)35Ar reaction. Both reaction channels are simulated with 1000000 particles.

Detector Small Detector Big Detector

position Ndet/Ntot [10−2] σReff [b] A35Ar [%] Ndet/Ntot [10−2] σReff [kb] A35Ar [%]

-3- 0.22 8.65 0 2.67 0.1 37.67

-4- 0.25 9.53 0 2.88 0.11 48.11

-5- 0.26 9.83 0 2.96 0.11 51.32

-7- 0.17 6.73 33.47 3.32 0.13 92.57

-8- 0.11 4.24 46.33 2.82 0.11 92.57

-9- 0.06 2.28 60.72 2.35 0.09 92.57

-10- 0.28 10.67 22.87 3.7 0.14 22.87

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36 CHAPTER 4. RESULTS

Table 4.11: Fraction of scattered beam inside the detector plane,Ndet/Ntot, and effective Rutherford cross section of elastic scattered particles,σReff, and detector coverage of fusion products,A35Ar, inside detector planes at Er = 916 keVfor different detector positions for 34mCl(p, γ)35Ar reaction. Both reaction channels are simulated with 1000000 particles.

Detector Small Detector Big Detector

position Ndet/Ntot [10−2] σReff [b] A35Ar [%] Ndet/Ntot [10−2] σReff [kb] A35Ar [%]

-3- 0.22 6.34 0 2.67 0.08 36.95

-4- 0.25 6.98 0 2.88 0.08 48

-5- 0.26 7.2 0 2.96 0.08 51.4

-7- 0.17 4.93 35.49 3.32 0.09 95.13

-8- 0.11 3.11 49.14 2.82 0.08 95.13

-9- 0.06 1.67 64.38 2.35 0.07 95.13

-10- 0.28 7.81 1.36 3.7 0.1 1.36 1st Detector Position 1 [3]

1 1st Detector Position 2 min [4]

1 1st Detector Position 2 max [5]

1 2nd Detector minimum Position [7]

1 2nd Detector middle Position [8]

1 2nd Detector maximum Position [9]

1

Figure 4.4: xyhit distribution for34mCl(p, γ)35Arat resonance energyEr= 916 keV: elastic scattering (mostly green with a big spike at the middle, forθ≥5) and fusion products (pattern superimposed on top of elastic scattered beam, on the right hand side) with two detector planes (big and small rectangle) on the different possible detector positions: dipole: a, b,c; after quadrupole: d,e,f; after first hexapole: g. The cutoffs are due to beam pipe restrictions.

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