1. Detecting Giant Monopole Resonances Peter Nguyen Advisors: Dr. Youngblood, Dr. Lui Texas A&M University

2. Giant Resonances Discovered in the early 1940s by bombarding nuclei with gamma rays Giant resonances is a collective motion of nucleons that occurs when the nucleus becomes excited Each mode has an associated multipole integer value L to represent the angular momentum transfer Classification  Isoscalar means the protons and neutrons move in phase and is denoted as ∆T = 0  Isovector means the protons and neutrons do not move out of phase and is denoted by ∆T = 1

3. Isoscalar Giant Monopole Resonances (ISGMR) ISGMR is the “breathing” mode where the nucleons compress and expand causing the nucleus’ radius to fluctuate ISGMR can be related to the nucleus, denoted as K nm

4. Motivation Behind K nm It is a fundamental quantity describing the ground state properties of nuclear matter Uses  Supernova collapses  Neutron stars  Heavy-ion collisions  Determine the Nuclear Equation of State Measuring it  Deduce information from the frequency of the compression mode of the nucleus during ISGMR and ISGDR  Relate the compressibility to the centroid energy of the ISGMR

5. Detection of ISGMR Difficult to detect because Giant Quadrupole Resonance GQR hid the GMR except at small scattering angles Beam analysis system provides a very clean beam which can be used in the measurement Using a beam of specific MeV, the beam will collide target nucleus

6. MDM Spectrometer The target nuclei in the target will excite to a higher energy level α particles with different energy will separate by MDM spectrometer and focus on different position of the detector

7. Stable Nuclei Excessive studies have been made on the stable nuclei by using alpha particles scattering Through inelastic scattering, information of ISGMR and ISGDR have been obtain from the stable nuclei ( 12 C - 208 Pb) Researcher are focusing more on unstable nuclei

8. Unstable Nuclei Unstable nuclei cannot be placed in the target chamber because of its decaying nature. The nuclei will immediately decay into another element To study the unstable nuclei, an inverse reaction is needed, the unstable nuclei becomes the projectile Detector on the back of spectrometer combined with decay detector inside target chamber to measure the resonance of unstable nucleus Reaction- 28 Si( 6 Li, 6 Li) 28 Si* Inverse Reaction - 6 Li ( 28 Si, 28 Si*) 6 Li

9. Decay Detector in Target Chamber The detector is compose of a thick scintillator block, and vertical and horizontal thin strips that are 1 mm thick The particles will go through the vertical strip first and then the horizontal strip. This will determine the position of the outgoing particles The scintillator block measures the energy of the particles

10. Scintillator  Sensitive to Energy Represented as a linear function  Fast Time Response Recovery time is short  Pulse Shape Discrimination Determining different particles A scintillator is a device that absorbs energy and emits light Several kinds of scintillating material exists including: organic, inorganic and plastic The particle hits the scintillator which excites the molecules in the scintillating material to emit light The photons released is then capture by a photomultiplier that is coupled to the scintillator via a light guide or directly attached

11. The photomultiplier absorbs the emitted light and electrons are release via photoelectric effect at the photocathode The cathode, dynodes, and the anodes create a potential “ladder” that directs the electrons The electrons travel from the photocathode to the first dynode and excite more electrons in the dynode The excited electrons leave the dynode and travel to the next dynode to repeat the process At the anode all the electrons are collected and then amplify to create a readable current Photomultiplier

12. Energy Loss Using SRIM, a program that computes the energy associated with scintillator thickness, the energy loss after striking the scintillator is calculated and subtracted from the initial energy

13. Energy Loss (cont.)

16. Light Output

17. Light Output Data Points Proton Final EnergyEnergy Loss 14.044549445.65449513 121.772584116.75876843 265.28279469.924787821 441.75244916.90586927 651.1278545.121702054 890.92178984.062224042 1161.516253.310228612 1459.5085392.89640396 1789.2319212.450009156 2147.2134822.119347153 2533.1279371.863983349 2946.9823211.648915691 3388.1358871.472603244 4348.1517631.272532761 Deuterium Final EnergyEnergy Loss 123.327010619.01374922 231.102612812.84648608 359.86412169.378536605 508.22550347.212428237 675.22447045.780727277 858.10536154.998311244 1061.2030034.221229134 1281.6682953.642717902 1519.5885043.178649471 1774.6516652.801073083 2046.3235682.502614581 2636.8830212.140732853 3295.2567361.779895568 4017.2990281.509377271 4801.7406741.303716468 5647.7037561.140994357 6554.1383081.012369008 7520.3381710.907226759 8545.6679340.818352334 9629.1864230.745711981 Tritium Final EnergyEnergy Loss 244.396325813.18231512 356.053378410.06235227 480.95308248.164524532 619.23718876.882279685 771.72362265.857644727 938.34660184.994116805 1116.993874.402916419 1309.2206873.875750442 1514.2423783.438651238 1958.5165152.937909656 2454.5349182.448657849 2998.9336582.06758188 3590.370121.776982275 4227.7748351.558597089 4911.1421511.375439938 5639.4224151.228612782 6412.2845741.104784763 7228.9737321.003203917 8089.200210.916022879 8992.5059980.8406453 9938.3867060.776116463 10926.467150.720301017 11956.519080.670081402 13027.934740.62749363 14141.67480.578068303 15295.168790.545017772 Alpha Final EnergyEnergy Loss 41.42294465135.6397697 110.897930993.82538113 186.316959173.28500163 270.126300459.42945228 360.718049349.73150895 457.888883942.55009296 561.518509737.01540361 790.548101928.43737153 1038.67095923.65732572 1309.1059920.47395873 1608.50126917.38504145 1929.62341215.18195948 2274.30566713.37833735 2640.26174612.04178611 3030.8048810.76934387 3442.1384139.804311112 3877.2429768.869569149 4332.7020428.150895245 4809.9341457.515757865 5308.6237916.955582819 5828.5849936.457850664 6368.3724556.066687325 6932.7916275.566141551 7513.1403655.296047997 8115.2943645.006635036 8739.0525394.70402281 9382.0083574.46208109 10046.196394.208325864 10729.413544.00329773 11432.531843.814142001 12154.451953.663975779 12898.078953.475189812

18. Identifying The Particle To verify the GMR, the monopole sum rule is used

19. Current Progress This holds the scintillator that will be place inside the target chamber

20. Current Progress (cont.) The high voltage will be control from upstairs with wire connecting from the ceiling

21. Current Progress (cont.) On top of the target chamber will be a ring that will be attach. The photomultipliers are then attach from the outside of the target chamber

22. Acknowledgement Dr. Youngblood Dr. Lui Xinfeng Chen Jonathan Button Robert Polis