Meeting Memo for P275

Measurement of (d,2p) and (d,d′) on 56Fe in inverse kinematics

Shinsuke OTA

December 19, 2011

Chapter 1

Goal of P275

We are aming at the first reaction measurement by using active target.

1.1 Physics Motivation

• Electron capture rate by Iron-group nuclei, relating to pre-stage of supernova. B(GT+),spin-dipole strength. (d,2He)

• Nuclear structure. Gamow-Teller strength distribution in neutron-rich nuclei.

• Incompressibility of nuclear matter. (d,d′)

1.2 Goal

We have developed an active target for high intensity (∼106−7 pps) and high energy (100−300 MeV)medium mass (A ∼ 50− 100) heavy ion beam. First goal of our project is to measure the Gamow-Teller strength in 56Ni, relating to the supernova explosion.

We need some tests of our system and analysis procedure, in this experiment. The items to bedone are listed below.

1. Basic property

(a) Evaluate the effect of δ-raysEvaluate the effect of δ rays when the beam particle go through active area directly. Hitpattern in readout pad may become different from single track.

(b) Measure the gain uniformity in GEMIrradiate 56Fe beam to whole the active area and compare the corrected charges in everypad with a correction for energy loss.

(c) Measure the drift velocityIrradiate 56Fe beam and µ-hodoscope, which is a position reference, for different electric-field setting and beam intensity.

2. Reconstruct (d,d’) events and making a excitation energy spectrum of (d,d’) on 56Fe

(a) reconstruct a track of particles

(b) make particle identification using dE-E or TOF-E method

(c) select single track of deuteron and make a two-dimensional plot of recoiled angle andkinematic energy

1

0.0001

0.001

0.01

0.1

1

0 2 4 6 8 10

thetaCM (deg)

j0(q(rad(x))*R)**2j1(q(rad(x))*R)**2j2(q(rad(x))*R)**2

Figure 1.1: Spherical Bessel function.

(d) calculate excitation energy from recoiled deuteron momentum

3. Reconstruct (d,2He) )events and making a excitation energy spectrum of 56Mn

(a) find two tracks which have a vertex

(b) reconstruct invariant mass of two protons

1.3 Theoretical calculations

1.3.1 Angular distribution

Spherical Bessel function JL(qR) is ploted in Fig. 1.1, where L indicates the angular momentumtransfer, q is the momentum transfer corresponding to θCM and R is the sum of the radii of 56Fenucleus and deuterium. The momentum transfer is calculated for the elastic scattering of 56Fe ondeuteron at 250 MeV/u incident energy. The gloss structure is not so different from the chargeexchange reaction 56Fe(d,2He) as shown in Fig. A.1. First peak of dipole excitation is expected tobe 2.

1.3.2 Kinematics

Figure 1.2 shows the kinematical correlation between the energy and recoiled angle of deuteron.The kinematics is calculated for 56Fe(d,d) elastic and inelastic scattering in inverse kinematics.Each line indicates the correlation in an excitation. Dots show the correlation every 1 deg. and1 MeV.

1.3.3 Range

To design the pad size, the ranges of proton and deuteron in 1-atm deuterium gas is calculated.Figure 1.3 shows the calculated ranges. The horizontal axis is the recoiled angle and the verticalaxis the kinetic energy in the unit of MeV per nucleon.

2

(deg)labθ80 82 84 86 88 90

(MeV

/u)

lab

E

0123456789

10

°=10CMθ

°=5CMθ

05Ex

Figure 1.2: Kinematics of 56Fe(d,d’) in inverse kinematics at 250 MeV/u. Correlation between theenergy and recoiled angle of deuteron is drawn. The vertical and horizontal axis are the energyand recoiled angle, respectively.

Kinetic Energy (MeV/u)0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Ran

ge (c

m)

0

1

2

3

4

5

6

7

8

9

10Ranges in 1-atm Deuterium Gas

protondeuteron

0 1 2 30

20

40

60

80

100

Figure 1.3: Ranges of deuteron and proton in 1-atm deuterium gas. The inset shows in wider range.

3

Chapter 2

Experimental Setup

Experimental setup and the requirement for each detector are described in this section.The experiment is performed at PH2 course of HIMAC, Chiba as shown in Fig. 2.1. Primary

beam of 56Fe is provided from the synchrotoron as debunched beam. Slow extraction will be applyto make the momentary intensity lower. The duty will be 60% of one spil, whose period is 3.3 sec.The intensity and energy will be 1 MHz and 250 MeV/u, respectively.

The 56Fe beam bombard the Active Target TPC filled with 100% D2 gas. Recoiled chargedparticles are detected TPC, and NaI array if the total kinetic energy is enough high to reach NaIcrystal. Beam-like scattered particles are detected by 1×1-mm2 plastic scintillarator hodoscope(µHodoscope) and 320µm-thick Si strip detector. The timing information of beam is provided byµHodoscope and the charge information by Si detector.

Course PH2 course1 of HIMAC, Chiba (Figure 2.1)

Beam Condition 56Fe 2, 250 AMeV, up to 108 pps, synchrotron, de-bunched, slow extraction1 spil = 3.3 sec., duty = 2/3.3 = 60%

2.1 TPC and Chamber

TPC consists of field cage, GEMs and readout pad and is used to measure the low-energy recoiledparticles. Three GEMs will be used to archieve the gas gain of more than 2000. The readout padconsists of 5-mm and 10-mm regular-triangle pads. The energy range is 0.3-0.6 and 0.3-0.8 MeV intotal for protons and deuterons, respectively. The higher-energy particles deposit smaller energyto the TPC. Then the maximum energy to be measured is set to be 8 MeV/u corresponding to5 keV/5mm denergy deposition.

Field cage ready but need to be moved to the new chamber

GEM Measuring the gain with triple GEM configuration.

Chamber will be ready untill the end of Dec., produced by CI

Readout pad will be ready until the end of Dec., produced by MATSUO

Preamplifier 8 RPA211 will be delivered by REPIC until the end of Dec.1totally 45-A electric supply2 DONE1:Submit the application of change of beam energy

4

Figure 2.1: Layout of experimental room

PLTPC beam dump

NaI

NaI56Fe

60x2-31x31x70 mm3 NaITd>2MeV

Tp>1.6MeV

1-10x10x25cm3 cageTd~0.3-0.8MeVTp~0.3-0.6MeV

dE>10keV/10mmTd < 16MeV

Tp<8MeV

30x2(XY)-1x1x30mm3 PLTiming

Position reference

340

collimatorbeam viewer

Si

1-5x5cm2 0.1mmt Si(5 mm strip)Trigger

beam viewer

newnew new

Figure 2.2: Schematic view of experimental setup.

5

Chamber

DeuteriumGas

Generator

Oxygen Monitor

Bubbler Balloon

Evacuation

Keep Pressure~1.01 atm

Nitrogen AtomosphereDeuterium GasBelow 4%

Mass Flow Controller

Keep FlowBelow 30cc/min

Injection Valve

Valve

Volume 200L

Figure 2.3: Schematic view of gas piping

Circuit 7 V1740 boards are ready for use. Pitch converter for the V1740 input will be deliveredby REPIC until the end of Dec.

Test Schedule Repaired system should be tested offline w/ alpha source∼11/30 test w/ Ar+CH4 gas, readout w/ new FADC (CAEN)∼12/10 test w/ D2 gas and double GEMs

2.2 Calorimeter

Calorimeter consists of 120 NaIs to measure the high-energy recoiled particles. The energy to bedetected is higher than 1.6 and 2 MeV in total and

NaI scintillator 120 piece of 31×31×50-mm3 NaI scintillators. Resolution measurement w/ γ-raysource until the end of Nov. The expected time resolution is 0.5 ps (FWHM) and shouled bemeasured.

Attachment ready

Power supply

Circuit basically ready, N568B, V785(ADC), V1190, C808(CFD) (CAMAC modules)

2.3 µ-Hodoscope

µ(micro)-Hodoscope consists of 60 piece of 1-mm×1-mm×30-mm scintillators for horizontal andvirtical axis. Scintillators are connected to multi-anode photomultiplier through contact with 1-mmsquare optical fiber. Picture is shown in Fig. 2.4. This detector will be used for the purpose aslisted below.

• Position reference to TPC tracking, especially in vertical direction.

• Timing reference of beam particle.

• Beam counter.

6

Figure 2.4: Photo of µ-Hodoscope in test experiment at RCNP. Only 30 pieces are ready.

The position is determined by using the geometrical position of each plastic peace with discrimi-nating the cross talks by software. In order to measure the charge information with high-intensitybeam, the outputs from PMT are amplified and discriminated by RPA-132 preamp.-discriminatorwith 16-ns decay constant. The RPA-132 output the leading and trailing edge of the pulse. Thewidth of the output pulse provides the pulse height information of PMT output.

Plastic scintillator 30 1×1×30-mm3 plastic scintillator along horizontal and virtical axis, respec-tively.

Holder designed and delivered

Circuit RPA132 and V1190 for anode, and V1190 and V792 for dynode

2.4 Trigger and Circuits

under construction

7

Chapter 3

Schedule

Beam time is allocated from Jan. 10th to 21st, 104 hours in total. Beam is basically availableduring nighttime, except on Suterday, 14th and 21st. On-site preparation will be start from 4th,Jan. We have 5 days for the preparation at HIMAC.

3.1 Schedule of preparation

12/16(Fri)

• Making item list for transportation

12/19 (Mon)

• 10:00-12:00 P275 Meeting at 2F meeting room in CNS

12/28 (Wed)

• all the ordered items should be delivered until this day

• pack all the items to be delivered

• NaIs should be attached to the flange

1/4 (Wed)

• 10:00 Transportation (Michimasa, Kubota, Yamaguchi)

• 13:00 Arrive at HIMAC (Ota, Tokieda, Dozono, Matsubara)

• 14:00? Items are arrived at HIMAC

• check items

1/10 (Tue)

• around 19:00 beam tuning start

3.2 Schedule of Beam Time

Beam time starts at 21:00 on 10th Jan and lasts until 20:00 on 21th Jan. There is no beam availablein daytime of weekday and weekend, then the total time of beam-on-target is 104 hours as shownin Fig. 3.1

8

Figure 3.1: Schedule of beam time and preparation, indicated by blue and red box, respectively.

9

3.2.1 Game Plan

1/10 (Tue)

Beam time starts at 21:00.

1. beam size and hodoscope

(a) Check beam size using ZnS and tuning to make spot size smaller than φ2 cm at theentrance and exit of the chamber.

(b) Start tuning the circuit for the hodoscope, at the same time. Trigger is hodoscopesingle and trigger timing is not delayed. Threshold of preamp is set if needed. Chargeinformation of dynode is only used for the correction of the width.

2. gamma-ray measurement with NaI array to correct timing offset and evaluate walk of timing

3. set the software threshold for TPC and tracking of beam

4. measure beam tracks with narrow and broadened beam to measure the gain uniformity, driftvelosity and rate dependence of them.

1/11 (Wed)

1. beam size tuning

2. circuit tuning for physics trigger

3. measurement of elastic scattering with modest intensity (105 Hz) beam

1/12 (Thu) - 1/14 (Sat)

1. beam size tuning every day

2. physics run 1

1/15 (Sun) - 1/16 (Mon)

1. data analysis, especially for elastic scattering

1/17 (Mon) - 1/21 (Sat)

1. beam size tuning every day

2. physics run 2

3.3 Schedule of Participants

Participants should be registered as user of HIMAC before experiment.

10

Name Affiliation Lecture Schedule Accomodation1 Shinsuke OTA CNS 1/4-1/23 1/4-1/232 Hiroshi TOKIEDA CNS 1/4-1/23 1/4-1/233 Masanori DOZONO Nishina 1/4-1/23 1/4-1/234 Hiroaki MATSUBARA CNS 1/4-1/23 1/4-1/235 Shin’ichiro MICHIMASA CNS 1/4-1/10 1/4-1/106 Yuki KUBOTA CNS 1/5 1/5-1/23 1/5-1/237 CheongSoo LEE CNS 1/5 1/5-1/23 1/5-1/238 Hidetoshi YAMAGUCHI CNS 1/5 1/5-1/08 1/5-1/089 Masami SAKO Kyoto 1/5-1/10 1/5-1/1010 Yosuke KIKUCHI CNS NONE NONE11 Shigeru KUBONO CNS TBA12 Takashi HASHIMOTO RCNP13 Tomohiro UESAKA Nishina14 Hideaki OTSU Nishina15 Yukie MAEDA Miyazaki16 Takahiro KAWABATA Kyoto TBA17 Eiichi TAKADA NIRS

11

Appendix A

A.1 Yield estimation

A.1.1 ACCBA calculation

Angle in c.m. frame (deg)0 2 4 6 8 10

(m

b/s

r)Ωdσd

-210

-110

1

He)2Fe(d,56

Figure A.1: Calculated differ-ential cross section.

A theoretical calculation can be done by using a calculation codecalled ACCBA. The exit optical potential are calculated in themanner described in Ref. . The entrance optical potential are as-sumed to be same as d-51V reaction at Ed = 172 MeV but thedepth of real part is decreaced manually almost same as the oneof imaginary part. The calculated differential cross section forEx = 1.7 MeV is shown in Fig. A.1.

A.1.2 Previous experiment

There are several studies on the Gamow-Teller strength in 56Fe nu-cleus with different probes and different energy. From these studieswe can estimate the yield of 2He in our charge exchange reactionat 250 MeV/u Figure A.2 shows the differential cross sections ofcharge exchange reactions. The (n,p) reactions with 198-MeV and97-MeV incident neutron energies are shown in Fig. A.2(a) and(b), respectively. Gamow-Teller strength is concentrated in the ex-citation energy range from 0 MeV to 5 MeV. The cross sectionsbecomes around 2 times larger when the incident energy becomeshigher. The result from (d,2He) reaction in normal kinematics isshown in Fig. A.2(c). The running sum up to 5 MeV is about2 mb/sr, which seems to be around a half of the (n,p) reactionwith En = 97 MeV. Although we don’t know both optical potentials of the entrance and exit chan-nel, assuming the energy dependence of the interaction is same as the one in (n,p) reaction, theexpected running sum of the differential cross section of 56Fe(d,2He) with Ed = 250 MeV is about4 mb/sr up to 5-MeV excitation energy. Note that the dipole strength at higher excitation energyis larger than Gamow-Teller strength as seen in Figure A.2(a).

A.1.3 YieldTarget

1.8 × 10−4 g/cm3 × 5 cm/2 g/mol × 6 × 1023/mol = 2.7 × 1020/cm2

Beam 106 pps

Cross section 0.030 mb = 3.0×10−29 /cm2 (0 < θcm < 10)

12

(a) 56Fe(n,p) En = 198 MeV

L i laCa

Éb

-0

3 0 . . . . =2 - 4°

44"

2

14+# t

+

4"

"

1 +

0

1

0

3

2

1

0

3

2

1

0

0 =10-12°

0 , -=18-20 '

F i g. 3. Exper i men t a l da t a a t se l ec t ed ang l es toge ther w i th the ca l cu l a t ed con t r i bu t i on f rom mu l t i s t epprocesses (do t t ed l i ne ) . The ca l cu l a t ed con t r i bu t i on f rom quas i f ree sca t t er i ng , us i ng va l ues o f the

energy cu to f f parame t er T o f 12 MeV (so l i d l i ne ) and 70 MeV (dashed l i ne ) i s a l so shown.

s4 Fe (n , p) , the ca l cu l a t ed fu l l cross sec t i ons (s i ng l e s t ep + mu l t i s t ep) are a l mos t af ac tor o f two sma l l er than the exper i men t a l da t a a t the l arges t ang l es o f th i sexper i men t . There fore , a Va va l ue o f 21 MeV was used , wh i ch g i ves be t t eragreemen t (F i g . 4) . As can be seen , the con t r i bu t i on f rom mu l t i s t ep processes i ssma l l , i n par t i cu l ar a t l ower exc i t a t i on energ i es . The ca l cu l a t ed mu l t i s t ep con t r i bu-t i ons vary smoo th l y w i th mass number (A) . The mu l t i s t ep ca l cu l a t i on for the54 Fe (n , p) reac t i on was there fore used as an es t i ma t e for the " Fe (n , p) reac t i on .

4 . 2 Ca l cu l a t i on o f angu l ar d i s t r i bu t i ons

T. Rönnqu i s t e t a l . / - " - - "Fe (n , p)

231

" Fe (n , p) s6Fe (n , p)

_ 0 , , =2-4*

0 , . =10-12°

E , (MeV)

0 10 20 30 0 10 20 30

To decompose the exper i men t a l da t a i n to d i f f eren t mu l t i po l ar i t i es , samp l e

angu l ar d i s t r i bu t i ons are needed . Angu l ar d i s t r i bu t i ons for severa l J~-va l ues were

(b) 56Fe(n,p) En = 97 MeV

d2!

/d"

dE [

mb/

(sr 4

0keV

)]

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0 2 4 6 8

0.2

0.4

0.6

0.8

B(G

T)+

Ex = 110 keV

Ex [MeV]

56Fe(d,2He)Ed = 172 MeVFWHM = 110 keV#cm ~ 0°

Centroid (2.2 MeV)

Centroid (1.9 MeV) expmtl. FFN#cm = 0-1.5°Ed = 183 MeV

-1 0 21 3 4 6 7 8 9 100

2

4

6

8

5Ex [MeV]

d!/d"

dE [a

rb. u

nits

]

10

1H(d,2He)n

Figure 4. Zero degree spectrum of the reaction 56Fe(d,2He) at 172 MeV incident energy (top).The shaded areas denote GT-transitions. In the lower part the results from a large shell modelcalculation (from Ref. [27]) is presented showing a remarkable level of agreement.

arrive at the opposite conclusion.In fig. 4 we show the zero-degree spectra of our latest experiments on 56Fe and 67Zn

together with a recent shell model calculation for 56Fe. A remarkable level of agreement isachieved in the case of 56Fe, whereas for 67Zn similar large scale shell model calculationsare at present still lacking.

2.1. The case of the odd-odd nucleus 50VThe 50V nucleus is the only stable odd-odd nucleus in the pf shell, and as the two

unpaired nucleons are both located in the f7/2 shell, they couple to a rather sizable ground-state spin of Jπ = 6+. The GT+ transitions will therefore lead to the Jπ = 5+, 6+ and 7+

states in the final nucleus 50Ti.Langanke et al. [28] argue that electron capture on odd-odd nuclei has the most dra-

matic consequences in a pre-supernova collapse. Unfortunately, there is no experimentalinformation available about Gamov-Teller strength distributions for odd-odd nuclei in thepf shell. Further, the two (unstable!) odd-odd nuclei 54Mn and 60Co are considered tobe the most effective electron capturing nuclei along the collapse trajectory of a SN [28],

D. Frekers / Nuclear Physics A 752 (2005) 580c–589c586c

(c) 56Fe(d,2He) Ed = 172 MeV

Figure A.2: Previous measurement of Gamow-Teller strength in 56Fe.

13

Duty 60%

Rate 2.7×1020 × 3.0×10−29 × 106 × 60% = 0.05 cps = ∼180 event / 10 hour (0-10 deg)

σ =∫

dσ

dΩdΩ (A.1)

=∫

dσ

dΩsin θdθdφ (A.2)

=∑

2πdσ

dΩsin θ∆θ (A.3)

Reaction simulation using GEANT4 is being prepared.Simple simulation for δ-ray event is done on 11/17.

A.2 Energetic knock-on electrons (δ-rays)

A.3 Properties of Nuclei

14

Contents

1 Goal of P275 11.1 Physics Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Goal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3 Theoretical calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.3.1 Angular distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.3.2 Kinematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.3.3 Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2 Experimental Setup 42.1 TPC and Chamber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42.2 Calorimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.3 µ-Hodoscope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.4 Trigger and Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

3 Schedule 83.1 Schedule of preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83.2 Schedule of Beam Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3.2.1 Game Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103.3 Schedule of Participants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

A 12A.1 Yield estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

A.1.1 ACCBA calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12A.1.2 Previous experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12A.1.3 Yield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

A.2 Energetic knock-on electrons (δ-rays) . . . . . . . . . . . . . . . . . . . . . . . . . . . 14A.3 Properties of Nuclei . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

15